Class: Sequel::Dataset
- Extended by:
- Metaprogramming
- Includes:
- Enumerable, SQL::AliasMethods, SQL::BooleanMethods, SQL::CastMethods, SQL::ComplexExpressionMethods, SQL::InequalityMethods, SQL::NumericMethods, SQL::OrderMethods, SQL::StringMethods
- Defined in:
- lib/sequel/dataset.rb,
lib/sequel/dataset/sql.rb,
lib/sequel/dataset/misc.rb,
lib/sequel/dataset/graph.rb,
lib/sequel/dataset/query.rb,
lib/sequel/dataset/actions.rb,
lib/sequel/dataset/features.rb,
lib/sequel/dataset/mutation.rb,
lib/sequel/extensions/query.rb,
lib/sequel/extensions/pagination.rb,
lib/sequel/adapters/utils/replace.rb,
lib/sequel/extensions/null_dataset.rb,
lib/sequel/extensions/split_array_nil.rb,
lib/sequel/dataset/prepared_statements.rb,
lib/sequel/adapters/utils/stored_procedures.rb
Overview
A dataset represents an SQL query, or more generally, an abstract set of rows in the database. Datasets can be used to create, retrieve, update and delete records.
Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely (datasets never cache results):
my_posts = DB[:posts].filter(:author => 'david') # no records are retrieved
my_posts.all # records are retrieved
my_posts.all # records are retrieved again
Most dataset methods return modified copies of the dataset (functional style), so you can reuse different datasets to access data:
posts = DB[:posts]
davids_posts = posts.filter(:author => 'david')
old_posts = posts.filter('stamp < ?', Date.today - 7)
davids_old_posts = davids_posts.filter('stamp < ?', Date.today - 7)
Datasets are Enumerable objects, so they can be manipulated using any of the Enumerable methods, such as map, inject, etc.
For more information, see the “Dataset Basics” guide.
Direct Known Subclasses
ADO::Dataset, Amalgalite::Dataset, Cubrid::Dataset, Sequel::DB2::Dataset, Sequel::DBI::Dataset, Sequel::DataObjects::Dataset, Firebird::Dataset, IBMDB::Dataset, Informix::Dataset, JDBC::Dataset, Mock::Dataset, MySQL::Dataset, Mysql2::Dataset, ODBC::Dataset, OpenBase::Dataset, Oracle::Dataset, Postgres::Dataset, SQLite::Dataset, Swift::Dataset, TinyTDS::Dataset
Defined Under Namespace
Modules: ArgumentMapper, NullDataset, Nullifiable, Pagination, PreparedStatementMethods, Replace, SplitArrayNil, StoredProcedureMethods, StoredProcedures, UnnumberedArgumentMapper Classes: Query
Constant Summary collapse
- OPTS =
Sequel::OPTS
- EMULATED_FUNCTION_MAP =
Map of emulated function names to native function names.
{}
- WILDCARD =
LiteralString.new('*').freeze
- ALL =
' ALL'.freeze
- AND_SEPARATOR =
" AND ".freeze
- APOS =
"'".freeze
- APOS_RE =
/'/.freeze
- ARRAY_EMPTY =
'(NULL)'.freeze
- AS =
' AS '.freeze
- ASC =
' ASC'.freeze
- BACKSLASH =
"\\".freeze
- BOOL_FALSE =
"'f'".freeze
- BOOL_TRUE =
"'t'".freeze
- BRACKET_CLOSE =
']'.freeze
- BRACKET_OPEN =
'['.freeze
- CASE_ELSE =
" ELSE ".freeze
- CASE_END =
" END)".freeze
- CASE_OPEN =
'(CASE'.freeze
- CASE_THEN =
" THEN ".freeze
- CASE_WHEN =
" WHEN ".freeze
- CAST_OPEN =
'CAST('.freeze
- COLON =
':'.freeze
- COLUMN_REF_RE1 =
Sequel::COLUMN_REF_RE1
- COLUMN_REF_RE2 =
Sequel::COLUMN_REF_RE2
- COLUMN_REF_RE3 =
Sequel::COLUMN_REF_RE3
- COMMA =
', '.freeze
- COMMA_SEPARATOR =
COMMA
- CONDITION_FALSE =
'(1 = 0)'.freeze
- CONDITION_TRUE =
'(1 = 1)'.freeze
- COUNT_FROM_SELF_OPTS =
[:distinct, :group, :sql, :limit, :offset, :compounds]
- COUNT_OF_ALL_AS_COUNT =
SQL::Function.new(:count, WILDCARD).as(:count)
- DATASET_ALIAS_BASE_NAME =
't'.freeze
- DEFAULT =
LiteralString.new('DEFAULT').freeze
- DEFAULT_VALUES =
" DEFAULT VALUES".freeze
- DELETE =
'DELETE'.freeze
- DELETE_CLAUSE_METHODS =
clause_methods(:delete, %w'delete from where')
- DESC =
' DESC'.freeze
- DISTINCT =
" DISTINCT".freeze
- DOT =
'.'.freeze
- DOUBLE_APOS =
"''".freeze
- DOUBLE_QUOTE =
'""'.freeze
- EQUAL =
' = '.freeze
- ESCAPE =
" ESCAPE ".freeze
- EXTRACT =
'extract('.freeze
- EXISTS =
['EXISTS '.freeze].freeze
- FOR_UPDATE =
' FOR UPDATE'.freeze
- FORMAT_DATE =
"'%Y-%m-%d'".freeze
- FORMAT_DATE_STANDARD =
"DATE '%Y-%m-%d'".freeze
- FORMAT_OFFSET =
"%+03i%02i".freeze
- FORMAT_TIMESTAMP_RE =
/%[Nz]/.freeze
- FORMAT_TIMESTAMP_USEC =
".%06d".freeze
- FORMAT_USEC =
'%N'.freeze
- FRAME_ALL =
"ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING".freeze
- FRAME_ROWS =
"ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW".freeze
- FROM =
' FROM '.freeze
- FUNCTION_EMPTY =
'()'.freeze
- GROUP_BY =
" GROUP BY ".freeze
- HAVING =
" HAVING ".freeze
- INSERT =
"INSERT".freeze
- INSERT_CLAUSE_METHODS =
clause_methods(:insert, %w'insert into columns values')
- INTO =
" INTO ".freeze
- IS_LITERALS =
{nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze
- IS_OPERATORS =
::Sequel::SQL::ComplexExpression::IS_OPERATORS
- LATERAL =
'LATERAL '.freeze
- LIKE_OPERATORS =
::Sequel::SQL::ComplexExpression::LIKE_OPERATORS
- LIMIT =
" LIMIT ".freeze
- N_ARITY_OPERATORS =
::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS
- NOT_SPACE =
'NOT '.freeze
- NULL =
"NULL".freeze
- NULLS_FIRST =
" NULLS FIRST".freeze
- NULLS_LAST =
" NULLS LAST".freeze
- OFFSET =
" OFFSET ".freeze
- ON =
' ON '.freeze
- ON_PAREN =
" ON (".freeze
- ORDER_BY =
" ORDER BY ".freeze
- ORDER_BY_NS =
"ORDER BY ".freeze
- OVER =
' OVER '.freeze
- PAREN_CLOSE =
')'.freeze
- PAREN_OPEN =
'('.freeze
- PAREN_SPACE_OPEN =
' ('.freeze
- PARTITION_BY =
"PARTITION BY ".freeze
- QUALIFY_KEYS =
[:select, :where, :having, :order, :group]
- QUESTION_MARK =
'?'.freeze
- QUESTION_MARK_RE =
/\?/.freeze
- QUOTE =
'"'.freeze
- QUOTE_RE =
/"/.freeze
- RETURNING =
" RETURNING ".freeze
- SELECT =
'SELECT'.freeze
- SELECT_CLAUSE_METHODS =
clause_methods(:select, %w'with select distinct columns from join where group having compounds order limit lock')
- SET =
' SET '.freeze
- SPACE =
' '.freeze
- SQL_WITH =
"WITH ".freeze
- SPACE_WITH =
" WITH ".freeze
- TILDE =
'~'.freeze
- TIMESTAMP_FORMAT =
"'%Y-%m-%d %H:%M:%S%N%z'".freeze
- STANDARD_TIMESTAMP_FORMAT =
"TIMESTAMP #{TIMESTAMP_FORMAT}".freeze
- TWO_ARITY_OPERATORS =
::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS
- REGEXP_OPERATORS =
::Sequel::SQL::ComplexExpression::REGEXP_OPERATORS
- UNDERSCORE =
'_'.freeze
- UPDATE =
'UPDATE'.freeze
- UPDATE_CLAUSE_METHODS =
clause_methods(:update, %w'update table set where')
- USING =
' USING ('.freeze
- VALUES =
" VALUES ".freeze
- V190 =
'1.9.0'.freeze
- WHERE =
" WHERE ".freeze
- NOTIMPL_MSG =
:section: 6 - Miscellaneous methods These methods don’t fit cleanly into another section.
"This method must be overridden in Sequel adapters".freeze
- ARRAY_ACCESS_ERROR_MSG =
'You cannot call Dataset#[] with an integer or with no arguments.'.freeze
- ARG_BLOCK_ERROR_MSG =
'Must use either an argument or a block, not both'.freeze
- IMPORT_ERROR_MSG =
'Using Sequel::Dataset#import an empty column array is not allowed'.freeze
- EXTENSIONS =
Hash of extension name symbols to callable objects to load the extension into the Dataset object (usually by extending it with a module defined in the extension).
{}
- COLUMN_CHANGE_OPTS =
The dataset options that require the removal of cached columns if changed.
[:select, :sql, :from, :join].freeze
- NON_SQL_OPTIONS =
Which options don’t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.
[:server, :defaults, :overrides, :graph, :eager_graph, :graph_aliases]
- CONDITIONED_JOIN_TYPES =
These symbols have _join methods created (e.g. inner_join) that call join_table with the symbol, passing along the arguments and block from the method call.
[:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left]
- UNCONDITIONED_JOIN_TYPES =
These symbols have _join methods created (e.g. natural_join) that call join_table with the symbol. They only accept a single table argument which is passed to join_table, and they raise an error if called with a block.
[:natural, :natural_left, :natural_right, :natural_full, :cross]
- JOIN_METHODS =
All methods that return modified datasets with a joined table added.
(CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table]
- QUERY_METHODS =
Methods that return modified datasets
(<<-METHS).split.map{|x| x.to_sym} + JOIN_METHODS add_graph_aliases and distinct except exclude exclude_having exclude_where filter for_update from from_self graph grep group group_and_count group_by having intersect invert limit lock_style naked or order order_append order_by order_more order_prepend qualify reverse reverse_order select select_all select_append select_group select_more server set_graph_aliases unfiltered ungraphed ungrouped union unlimited unordered where with with_recursive with_sql METHS
- ACTION_METHODS =
Action methods defined by Sequel that execute code on the database.
(<<-METHS).split.map{|x| x.to_sym} << [] all avg count columns columns! delete each empty? fetch_rows first first! get import insert interval last map max min multi_insert paged_each range select_hash select_hash_groups select_map select_order_map single_record single_value sum to_hash to_hash_groups truncate update METHS
- MUTATION_METHODS =
All methods that should have a ! method added that modifies the receiver.
QUERY_METHODS - [:naked, :from_self]
- PREPARED_ARG_PLACEHOLDER =
:section: 8 - Methods related to prepared statements or bound variables On some adapters, these use native prepared statements and bound variables, on others support is emulated. For details, see the “Prepared Statements/Bound Variables” guide.
LiteralString.new('?').freeze
Instance Attribute Summary collapse
-
#db ⇒ Object
readonly
The database related to this dataset.
-
#opts ⇒ Object
readonly
The hash of options for this dataset, keys are symbols.
-
#row_proc ⇒ Object
The row_proc for this database, should be any object that responds to
call
with a single hash argument and returns the object you want #each to return.
Class Method Summary collapse
-
.clause_methods(type, clauses) ⇒ Object
Given a type (e.g. select) and an array of clauses, return an array of methods to call to build the SQL string.
-
.def_mutation_method(*meths) ⇒ Object
Setup mutation (e.g. filter!) methods.
-
.register_extension(ext, mod = nil, &block) ⇒ Object
Register an extension callback for Dataset objects.
Instance Method Summary collapse
-
#<<(arg) ⇒ Object
Inserts the given argument into the database.
-
#==(o) ⇒ Object
Define a hash value such that datasets with the same DB, opts, and SQL will be considered equal.
-
#[](*conditions) ⇒ Object
Returns the first record matching the conditions.
-
#add_graph_aliases(graph_aliases) ⇒ Object
Adds the given graph aliases to the list of graph aliases to use, unlike
set_graph_aliases
, which replaces the list (the equivalent ofselect_more
when graphing). -
#aliased_expression_sql_append(sql, ae) ⇒ Object
SQL fragment for AliasedExpression.
-
#all(&block) ⇒ Object
Returns an array with all records in the dataset.
-
#and(*cond, &block) ⇒ Object
Alias for where.
-
#array_sql_append(sql, a) ⇒ Object
SQL fragment for Array.
-
#avg(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the average value for the given column/expression.
-
#bind(bind_vars = {}) ⇒ Object
Set the bind variables to use for the call.
-
#boolean_constant_sql_append(sql, constant) ⇒ Object
SQL fragment for BooleanConstants.
-
#call(type, bind_variables = {}, *values, &block) ⇒ Object
For the given type (:select, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash.
-
#case_expression_sql_append(sql, ce) ⇒ Object
SQL fragment for CaseExpression.
-
#cast_sql_append(sql, expr, type) ⇒ Object
SQL fragment for the SQL CAST expression.
-
#clone(opts = nil) ⇒ Object
Returns a new clone of the dataset with with the given options merged.
-
#column_all_sql_append(sql, ca) ⇒ Object
SQL fragment for specifying all columns in a given table.
-
#columns ⇒ Object
Returns the columns in the result set in order as an array of symbols.
-
#columns! ⇒ Object
Ignore any cached column information and perform a query to retrieve a row in order to get the columns.
-
#complex_expression_sql_append(sql, op, args) ⇒ Object
SQL fragment for the complex expression.
-
#constant_sql_append(sql, constant) ⇒ Object
SQL fragment for constants.
-
#count(arg = (no_arg=true), &block) ⇒ Object
Returns the number of records in the dataset.
-
#delayed_evaluation_sql_append(sql, callable) ⇒ Object
SQL fragment for delayed evaluations, evaluating the object and literalizing the returned value.
-
#delete(&block) ⇒ Object
Deletes the records in the dataset.
-
#delete_sql ⇒ Object
Returns a DELETE SQL query string.
-
#distinct(*args) ⇒ Object
Returns a copy of the dataset with the SQL DISTINCT clause.
-
#dup ⇒ Object
Similar to #clone, but returns an unfrozen clone if the receiver is frozen.
-
#each ⇒ Object
Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.
-
#each_server ⇒ Object
Yield a dataset for each server in the connection pool that is tied to that server.
-
#empty? ⇒ Boolean
Returns true if no records exist in the dataset, false otherwise.
-
#emulated_function_sql_append(sql, f) ⇒ Object
SQL fragment specifying an emulated SQL function call.
-
#eql?(o) ⇒ Boolean
Alias for ==.
-
#escape_like(string) ⇒ Object
Returns the string with the LIKE metacharacters (% and _) escaped.
-
#except(dataset, opts = OPTS) ⇒ Object
Adds an EXCEPT clause using a second dataset object.
-
#exclude(*cond, &block) ⇒ Object
Performs the inverse of Dataset#where.
-
#exclude_having(*cond, &block) ⇒ Object
Inverts the given conditions and adds them to the HAVING clause.
-
#exclude_where(*cond, &block) ⇒ Object
Alias for exclude.
-
#exists ⇒ Object
Returns an EXISTS clause for the dataset as a
LiteralString
. -
#extension(*exts) ⇒ Object
Return a clone of the dataset loaded with the extensions, see #extension!.
-
#extension!(*exts) ⇒ Object
Load an extension into the receiver.
-
#filter(*cond, &block) ⇒ Object
Alias for where.
-
#first(*args, &block) ⇒ Object
If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit.
-
#first!(*args, &block) ⇒ Object
Calls first.
-
#first_source ⇒ Object
Alias of
first_source_alias
. -
#first_source_alias ⇒ Object
The first source (primary table) for this dataset.
-
#first_source_table ⇒ Object
The first source (primary table) for this dataset.
-
#for_update ⇒ Object
Returns a cloned dataset with a :update lock style.
-
#freeze ⇒ Object
Sets the frozen flag on the dataset, so you can’t modify it.
-
#from(*source, &block) ⇒ Object
Returns a copy of the dataset with the source changed.
-
#from_self(opts = OPTS) ⇒ Object
Returns a dataset selecting from the current dataset.
-
#from_self!(*args, &block) ⇒ Object
Avoid self-referential dataset by cloning.
-
#frozen? ⇒ Boolean
Whether the object is frozen.
-
#function_sql_append(sql, f) ⇒ Object
SQL fragment specifying an SQL function call without emulation.
-
#get(column = (no_arg=true; nil), &block) ⇒ Object
Return the column value for the first matching record in the dataset.
-
#graph(dataset, join_conditions = nil, options = OPTS, &block) ⇒ Object
Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.
-
#grep(columns, patterns, opts = OPTS) ⇒ Object
Match any of the columns to any of the patterns.
-
#group(*columns, &block) ⇒ Object
Returns a copy of the dataset with the results grouped by the value of the given columns.
-
#group_and_count(*columns, &block) ⇒ Object
Returns a dataset grouped by the given column with count by group.
-
#group_by(*columns, &block) ⇒ Object
Alias of group.
-
#group_cube ⇒ Object
Adds the appropriate CUBE syntax to GROUP BY.
-
#group_rollup ⇒ Object
Adds the appropriate ROLLUP syntax to GROUP BY.
-
#hash ⇒ Object
Define a hash value such that datasets with the same DB, opts, and SQL will have the same hash value.
-
#having(*cond, &block) ⇒ Object
Returns a copy of the dataset with the HAVING conditions changed.
-
#identifier_input_method ⇒ Object
The String instance method to call on identifiers before sending them to the database.
-
#identifier_input_method=(v) ⇒ Object
Set the method to call on identifiers going into the database for this dataset.
-
#identifier_output_method ⇒ Object
The String instance method to call on identifiers before sending them to the database.
-
#identifier_output_method=(v) ⇒ Object
Set the method to call on identifiers coming the database for this dataset.
-
#import(columns, values, opts = OPTS) ⇒ Object
Inserts multiple records into the associated table.
-
#initialize(db) ⇒ Dataset
constructor
Constructs a new Dataset instance with an associated database and options.
-
#insert(*values, &block) ⇒ Object
Inserts values into the associated table.
-
#insert_sql(*values) ⇒ Object
Returns an INSERT SQL query string.
-
#inspect ⇒ Object
Returns a string representation of the dataset including the class name and the corresponding SQL select statement.
-
#intersect(dataset, opts = OPTS) ⇒ Object
Adds an INTERSECT clause using a second dataset object.
-
#interval(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the interval between minimum and maximum values for the given column/expression.
-
#invert ⇒ Object
Inverts the current WHERE and HAVING clauses.
-
#join(*args, &block) ⇒ Object
Alias of
inner_join
. -
#join_clause_sql_append(sql, jc) ⇒ Object
SQL fragment specifying a JOIN clause without ON or USING.
-
#join_on_clause_sql_append(sql, jc) ⇒ Object
SQL fragment specifying a JOIN clause with ON.
-
#join_table(type, table, expr = nil, options = OPTS, &block) ⇒ Object
Returns a joined dataset.
-
#join_using_clause_sql_append(sql, jc) ⇒ Object
SQL fragment specifying a JOIN clause with USING.
-
#last(*args, &block) ⇒ Object
Reverses the order and then runs #first with the given arguments and block.
-
#lateral ⇒ Object
Marks this dataset as a lateral dataset.
-
#limit(l, o = (no_offset = true; nil)) ⇒ Object
If given an integer, the dataset will contain only the first l results.
-
#literal_append(sql, v) ⇒ Object
Returns a literal representation of a value to be used as part of an SQL expression.
-
#lock_style(style) ⇒ Object
Returns a cloned dataset with the given lock style.
-
#map(column = nil, &block) ⇒ Object
Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of
Enumerable
otherwise. -
#max(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the maximum value for the given column/expression.
-
#min(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the minimum value for the given column/expression.
-
#multi_insert(hashes, opts = OPTS) ⇒ Object
This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:.
-
#multi_insert_sql(columns, values) ⇒ Object
Returns an array of insert statements for inserting multiple records.
-
#naked ⇒ Object
Returns a cloned dataset without a row_proc.
-
#naked! ⇒ Object
Remove the row_proc from the current dataset.
-
#negative_boolean_constant_sql_append(sql, constant) ⇒ Object
SQL fragment for NegativeBooleanConstants.
-
#or(*cond, &block) ⇒ Object
Adds an alternate filter to an existing filter using OR.
-
#order(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order changed.
-
#order_append(*columns, &block) ⇒ Object
Alias of order_more, for naming consistency with order_prepend.
-
#order_by(*columns, &block) ⇒ Object
Alias of order.
-
#order_more(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order columns added to the end of the existing order.
-
#order_prepend(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order columns added to the beginning of the existing order.
-
#ordered_expression_sql_append(sql, oe) ⇒ Object
SQL fragment for the ordered expression, used in the ORDER BY clause.
-
#paged_each(opts = OPTS) ⇒ Object
Yields each row in the dataset, but interally uses multiple queries as needed with limit and offset to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.
-
#placeholder_literal_string_sql_append(sql, pls) ⇒ Object
SQL fragment for a literal string with placeholders.
-
#prepare(type, name = nil, *values) ⇒ Object
Prepare an SQL statement for later execution.
-
#provides_accurate_rows_matched? ⇒ Boolean
Whether this dataset will provide accurate number of rows matched for delete and update statements.
-
#qualified_identifier_sql_append(sql, table, column = (c = table.column; table = table.table; c)) ⇒ Object
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table).
-
#qualify(table = first_source) ⇒ Object
Qualify to the given table, or first source if no table is given.
-
#quote_identifier_append(sql, name) ⇒ Object
Adds quoting to identifiers (columns and tables).
-
#quote_identifiers=(v) ⇒ Object
Set whether to quote identifiers for this dataset.
-
#quote_identifiers? ⇒ Boolean
Whether this dataset quotes identifiers.
-
#quote_schema_table_append(sql, table) ⇒ Object
Separates the schema from the table and returns a string with them quoted (if quoting identifiers).
-
#quoted_identifier_append(sql, name) ⇒ Object
This method quotes the given name with the SQL standard double quote.
-
#range(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns a
Range
instance made from the minimum and maximum values for the given column/expression. -
#recursive_cte_requires_column_aliases? ⇒ Boolean
Whether you must use a column alias list for recursive CTEs (false by default).
-
#requires_placeholder_type_specifiers? ⇒ Boolean
Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer).
-
#requires_sql_standard_datetimes? ⇒ Boolean
Whether the dataset requires SQL standard datetimes (false by default, as most allow strings with ISO 8601 format).
-
#returning(*values) ⇒ Object
Modify the RETURNING clause, only supported on a few databases.
-
#reverse(*order, &block) ⇒ Object
Returns a copy of the dataset with the order reversed.
-
#reverse_order(*order, &block) ⇒ Object
Alias of
reverse
. -
#row_number_column ⇒ Object
The alias to use for the row_number column, used when emulating OFFSET support and for eager limit strategies.
-
#schema_and_table(table_name, sch = nil) ⇒ Object
Split the schema information from the table, returning two strings, one for the schema and one for the table.
-
#select(*columns, &block) ⇒ Object
Returns a copy of the dataset with the columns selected changed to the given columns.
-
#select_all(*tables) ⇒ Object
Returns a copy of the dataset selecting the wildcard if no arguments are given.
-
#select_append(*columns, &block) ⇒ Object
Returns a copy of the dataset with the given columns added to the existing selected columns.
-
#select_group(*columns, &block) ⇒ Object
Set both the select and group clauses with the given
columns
. -
#select_hash(key_column, value_column) ⇒ Object
Returns a hash with key_column values as keys and value_column values as values.
-
#select_hash_groups(key_column, value_column) ⇒ Object
Returns a hash with key_column values as keys and an array of value_column values.
-
#select_map(column = nil, &block) ⇒ Object
Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset.
-
#select_more(*columns, &block) ⇒ Object
Alias for select_append.
-
#select_order_map(column = nil, &block) ⇒ Object
The same as select_map, but in addition orders the array by the column.
-
#select_sql ⇒ Object
Returns a SELECT SQL query string.
-
#server(servr) ⇒ Object
Set the server for this dataset to use.
-
#set_graph_aliases(graph_aliases) ⇒ Object
This allows you to manually specify the graph aliases to use when using graph.
-
#single_record ⇒ Object
Returns the first record in the dataset, or nil if the dataset has no records.
-
#single_value ⇒ Object
Returns the first value of the first record in the dataset.
-
#split_alias(c) ⇒ Object
Splits a possible implicit alias in
c
, handling both SQL::AliasedExpressions and Symbols. -
#split_qualifiers(table_name, *args) ⇒ Object
Splits table_name into an array of strings.
-
#sql ⇒ Object
Same as
select_sql
, not aliased directly to make subclassing simpler. -
#subscript_sql_append(sql, s) ⇒ Object
SQL fragment for specifying subscripts (SQL array accesses).
-
#sum(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the sum for the given column/expression.
-
#supports_cte?(type = :select) ⇒ Boolean
Whether the dataset supports common table expressions (the WITH clause).
-
#supports_cte_in_subqueries? ⇒ Boolean
Whether the dataset supports common table expressions (the WITH clause) in subqueries.
-
#supports_distinct_on? ⇒ Boolean
Whether the dataset supports or can emulate the DISTINCT ON clause, false by default.
-
#supports_group_cube? ⇒ Boolean
Whether the dataset supports CUBE with GROUP BY.
-
#supports_group_rollup? ⇒ Boolean
Whether the dataset supports ROLLUP with GROUP BY.
-
#supports_insert_select? ⇒ Boolean
Whether this dataset supports the
insert_select
method for returning all columns values directly from an insert query. -
#supports_intersect_except? ⇒ Boolean
Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.
-
#supports_intersect_except_all? ⇒ Boolean
Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.
-
#supports_is_true? ⇒ Boolean
Whether the dataset supports the IS TRUE syntax.
-
#supports_join_using? ⇒ Boolean
Whether the dataset supports the JOIN table USING (column1, …) syntax.
-
#supports_lateral_subqueries? ⇒ Boolean
Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses.
-
#supports_modifying_joins? ⇒ Boolean
Whether modifying joined datasets is supported.
-
#supports_multiple_column_in? ⇒ Boolean
Whether the IN/NOT IN operators support multiple columns when an array of values is given.
-
#supports_ordered_distinct_on? ⇒ Boolean
Whether the dataset supports or can fully emulate the DISTINCT ON clause, including respecting the ORDER BY clause, false by default.
-
#supports_regexp? ⇒ Boolean
Whether the dataset supports pattern matching by regular expressions.
-
#supports_replace? ⇒ Boolean
Whether the dataset supports REPLACE syntax, false by default.
-
#supports_returning?(type) ⇒ Boolean
Whether the RETURNING clause is supported for the given type of query.
-
#supports_select_all_and_column? ⇒ Boolean
Whether the database supports SELECT *, column FROM table.
-
#supports_timestamp_timezones? ⇒ Boolean
Whether the dataset supports timezones in literal timestamps.
-
#supports_timestamp_usecs? ⇒ Boolean
Whether the dataset supports fractional seconds in literal timestamps.
-
#supports_where_true? ⇒ Boolean
Whether the dataset supports WHERE TRUE (or WHERE 1 for databases that that use 1 for true).
-
#supports_window_functions? ⇒ Boolean
Whether the dataset supports window functions.
-
#to_hash(key_column, value_column = nil) ⇒ Object
Returns a hash with one column used as key and another used as value.
-
#to_hash_groups(key_column, value_column = nil) ⇒ Object
Returns a hash with one column used as key and the values being an array of column values.
-
#truncate ⇒ Object
Truncates the dataset.
-
#truncate_sql ⇒ Object
Returns a TRUNCATE SQL query string.
-
#unbind ⇒ Object
Unbind bound variables from this dataset’s filter and return an array of two objects.
-
#unfiltered ⇒ Object
Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.
-
#ungraphed ⇒ Object
Remove the splitting of results into subhashes, and all metadata related to the current graph (if any).
-
#ungrouped ⇒ Object
Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.
-
#union(dataset, opts = OPTS) ⇒ Object
Adds a UNION clause using a second dataset object.
-
#unlimited ⇒ Object
Returns a copy of the dataset with no limit or offset.
-
#unordered ⇒ Object
Returns a copy of the dataset with no order.
-
#unused_table_alias(table_alias, used_aliases = []) ⇒ Object
Creates a unique table alias that hasn’t already been used in the dataset.
-
#update(values = OPTS, &block) ⇒ Object
Updates values for the dataset.
-
#update_sql(values = OPTS) ⇒ Object
Formats an UPDATE statement using the given values.
-
#where(*cond, &block) ⇒ Object
Returns a copy of the dataset with the given WHERE conditions imposed upon it.
-
#window_function_sql_append(sql, function, window) ⇒ Object
The SQL fragment for the given window function’s function and window.
-
#window_sql_append(sql, opts) ⇒ Object
The SQL fragment for the given window’s options.
-
#with(name, dataset, opts = OPTS) ⇒ Object
Add a common table expression (CTE) with the given name and a dataset that defines the CTE.
-
#with_recursive(name, nonrecursive, recursive, opts = OPTS) ⇒ Object
Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE.
-
#with_sql(sql, *args) ⇒ Object
Returns a copy of the dataset with the static SQL used.
-
#with_sql_delete(sql) ⇒ Object
Execute the given SQL and return the number of rows deleted.
Methods included from Metaprogramming
Methods included from SQL::StringMethods
Methods included from SQL::OrderMethods
Methods included from SQL::NumericMethods
Methods included from SQL::ComplexExpressionMethods
#extract, #sql_boolean, #sql_number, #sql_string
Methods included from SQL::CastMethods
#cast, #cast_numeric, #cast_string
Methods included from SQL::BooleanMethods
Methods included from SQL::AliasMethods
Constructor Details
#initialize(db) ⇒ Dataset
Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:
DB[:posts]
Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.
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# File 'lib/sequel/dataset/misc.rb', line 28 def initialize(db) @db = db @opts = OPTS end |
Instance Attribute Details
#db ⇒ Object (readonly)
The database related to this dataset. This is the Database instance that will execute all of this dataset’s queries.
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# File 'lib/sequel/dataset/misc.rb', line 15 def db @db end |
#opts ⇒ Object (readonly)
The hash of options for this dataset, keys are symbols.
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# File 'lib/sequel/dataset/misc.rb', line 18 def opts @opts end |
#row_proc ⇒ Object
The row_proc for this database, should be any object that responds to call
with a single hash argument and returns the object you want #each to return.
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# File 'lib/sequel/dataset/mutation.rb', line 31 def row_proc @row_proc end |
Class Method Details
.clause_methods(type, clauses) ⇒ Object
Given a type (e.g. select) and an array of clauses, return an array of methods to call to build the SQL string.
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# File 'lib/sequel/dataset/sql.rb', line 177 def self.clause_methods(type, clauses) clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze end |
.def_mutation_method(*meths) ⇒ Object
Setup mutation (e.g. filter!) methods. These operate the same as the non-! methods, but replace the options of the current dataset with the options of the resulting dataset.
Do not call this method with untrusted input, as that can result in arbitrary code execution.
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# File 'lib/sequel/dataset/mutation.rb', line 17 def self.def_mutation_method(*meths) = meths.pop if meths.last.is_a?(Hash) mod = [:module] if mod ||= self meths.each do |meth| mod.class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__) end end |
.register_extension(ext, mod = nil, &block) ⇒ Object
Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should either be a Module that the dataset is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.
If mod is a module, this also registers a Database extension that will extend all of the database’s datasets.
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# File 'lib/sequel/dataset/query.rb', line 53 def self.register_extension(ext, mod=nil, &block) if mod raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block if mod.is_a?(Module) block = proc{|ds| ds.extend(mod)} Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)} else block = mod end end Sequel.synchronize{EXTENSIONS[ext] = block} end |
Instance Method Details
#<<(arg) ⇒ Object
Inserts the given argument into the database. Returns self so it can be used safely when chaining:
DB[:items] << {:id=>0, :name=>'Zero'} << DB[:old_items].select(:id, name)
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# File 'lib/sequel/dataset/actions.rb', line 22 def <<(arg) insert(arg) self end |
#==(o) ⇒ Object
Define a hash value such that datasets with the same DB, opts, and SQL will be considered equal.
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# File 'lib/sequel/dataset/misc.rb', line 35 def ==(o) o.is_a?(self.class) && db == o.db && opts == o.opts && sql == o.sql end |
#[](*conditions) ⇒ Object
Returns the first record matching the conditions. Examples:
DB[:table][:id=>1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=1}
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# File 'lib/sequel/dataset/actions.rb', line 31 def [](*conditions) raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0 first(*conditions) end |
#add_graph_aliases(graph_aliases) ⇒ Object
Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases
, which replaces the list (the equivalent of select_more
when graphing). See set_graph_aliases
.
DB[:table].add_graph_aliases(:some_alias=>[:table, :column])
# SELECT ..., table.column AS some_alias
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# File 'lib/sequel/dataset/graph.rb', line 16 def add_graph_aliases(graph_aliases) unless (ga = opts[:graph_aliases]) || (opts[:graph] && (ga = opts[:graph][:column_aliases])) raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases" end columns, graph_aliases = graph_alias_columns(graph_aliases) select_more(*columns).clone(:graph_aliases => ga.merge(graph_aliases)) end |
#aliased_expression_sql_append(sql, ae) ⇒ Object
SQL fragment for AliasedExpression
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# File 'lib/sequel/dataset/sql.rb', line 299 def aliased_expression_sql_append(sql, ae) literal_append(sql, ae.expression) as_sql_append(sql, ae.aliaz) end |
#all(&block) ⇒ Object
Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.
DB[:table].all # SELECT * FROM table
# => [{:id=>1, ...}, {:id=>2, ...}, ...]
# Iterate over all rows in the table
DB[:table].all{|row| p row}
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# File 'lib/sequel/dataset/actions.rb', line 44 def all(&block) a = [] each{|r| a << r} post_load(a) a.each(&block) if block a end |
#and(*cond, &block) ⇒ Object
Alias for where.
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# File 'lib/sequel/dataset/query.rb', line 67 def and(*cond, &block) where(*cond, &block) end |
#array_sql_append(sql, a) ⇒ Object
SQL fragment for Array
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# File 'lib/sequel/dataset/sql.rb', line 305 def array_sql_append(sql, a) if a.empty? sql << ARRAY_EMPTY else sql << PAREN_OPEN expression_list_append(sql, a) sql << PAREN_CLOSE end end |
#avg(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the average value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1
# => 3
DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1
# => 1
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# File 'lib/sequel/dataset/actions.rb', line 59 def avg(column=Sequel.virtual_row(&Proc.new)) aggregate_dataset.get{avg(column).as(:avg)} end |
#bind(bind_vars = {}) ⇒ Object
Set the bind variables to use for the call. If bind variables have already been set for this dataset, they are updated with the contents of bind_vars.
DB[:table].filter(:id=>:$id).bind(:id=>1).call(:first)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
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# File 'lib/sequel/dataset/prepared_statements.rb', line 217 def bind(bind_vars={}) clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars) end |
#boolean_constant_sql_append(sql, constant) ⇒ Object
SQL fragment for BooleanConstants
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# File 'lib/sequel/dataset/sql.rb', line 316 def boolean_constant_sql_append(sql, constant) if (constant == true || constant == false) && !supports_where_true? sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE) else literal_append(sql, constant) end end |
#call(type, bind_variables = {}, *values, &block) ⇒ Object
For the given type (:select, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash. values
is a hash passed to insert or update (if one of those types is used), which may contain placeholders.
DB[:table].filter(:id=>:$id).call(:first, :id=>1)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
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# File 'lib/sequel/dataset/prepared_statements.rb', line 228 def call(type, bind_variables={}, *values, &block) prepare(type, nil, *values).call(bind_variables, &block) end |
#case_expression_sql_append(sql, ce) ⇒ Object
SQL fragment for CaseExpression
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# File 'lib/sequel/dataset/sql.rb', line 325 def case_expression_sql_append(sql, ce) sql << CASE_OPEN if ce.expression? sql << SPACE literal_append(sql, ce.expression) end w = CASE_WHEN t = CASE_THEN ce.conditions.each do |c,r| sql << w literal_append(sql, c) sql << t literal_append(sql, r) end sql << CASE_ELSE literal_append(sql, ce.default) sql << CASE_END end |
#cast_sql_append(sql, expr, type) ⇒ Object
SQL fragment for the SQL CAST expression
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# File 'lib/sequel/dataset/sql.rb', line 345 def cast_sql_append(sql, expr, type) sql << CAST_OPEN literal_append(sql, expr) sql << AS << db.cast_type_literal(type).to_s sql << PAREN_CLOSE end |
#clone(opts = nil) ⇒ Object
Returns a new clone of the dataset with with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted. This method should generally not be called directly by user code.
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# File 'lib/sequel/dataset/query.rb', line 75 def clone(opts = nil) c = super() if opts c.instance_variable_set(:@opts, @opts.merge(opts)) c.instance_variable_set(:@columns, nil) if @columns && !opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)} else c.instance_variable_set(:@opts, @opts.dup) end c end |
#column_all_sql_append(sql, ca) ⇒ Object
SQL fragment for specifying all columns in a given table
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# File 'lib/sequel/dataset/sql.rb', line 353 def column_all_sql_append(sql, ca) qualified_identifier_sql_append(sql, ca.table, WILDCARD) end |
#columns ⇒ Object
Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.
If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema
.
DB[:table].columns
# => [:id, :name]
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# File 'lib/sequel/dataset/actions.rb', line 72 def columns return @columns if @columns ds = unfiltered.unordered.naked.clone(:distinct => nil, :limit => 1, :offset=>nil) ds.each{break} @columns = ds.instance_variable_get(:@columns) @columns || [] end |
#columns! ⇒ Object
Ignore any cached column information and perform a query to retrieve a row in order to get the columns.
DB[:table].columns!
# => [:id, :name]
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# File 'lib/sequel/dataset/actions.rb', line 85 def columns! @columns = nil columns end |
#complex_expression_sql_append(sql, op, args) ⇒ Object
SQL fragment for the complex expression.
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# File 'lib/sequel/dataset/sql.rb', line 358 def complex_expression_sql_append(sql, op, args) case op when *IS_OPERATORS r = args.at(1) if r.nil? || supports_is_true? raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r] sql << PAREN_OPEN literal_append(sql, args.at(0)) sql << SPACE << op.to_s << SPACE sql << val << PAREN_CLOSE elsif op == :IS complex_expression_sql_append(sql, :"=", args) else complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)]) end when :IN, :"NOT IN" cols = args.at(0) vals = args.at(1) col_array = true if cols.is_a?(Array) if vals.is_a?(Array) val_array = true empty_val_array = vals == [] end if empty_val_array literal_append(sql, empty_array_value(op, cols)) elsif col_array if !supports_multiple_column_in? if val_array expr = SQL::BooleanExpression.new(:OR, *vals.to_a.map{|vs| SQL::BooleanExpression.from_value_pairs(cols.to_a.zip(vs).map{|c, v| [c, v]})}) literal_append(sql, op == :IN ? expr : ~expr) else old_vals = vals vals = vals.naked if vals.is_a?(Sequel::Dataset) vals = vals.to_a val_cols = old_vals.columns complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}]) end else # If the columns and values are both arrays, use array_sql instead of # literal so that if values is an array of two element arrays, it # will be treated as a value list instead of a condition specifier. sql << PAREN_OPEN literal_append(sql, cols) sql << SPACE << op.to_s << SPACE if val_array array_sql_append(sql, vals) else literal_append(sql, vals) end sql << PAREN_CLOSE end else sql << PAREN_OPEN literal_append(sql, cols) sql << SPACE << op.to_s << SPACE literal_append(sql, vals) sql << PAREN_CLOSE end when :LIKE, :'NOT LIKE' sql << PAREN_OPEN literal_append(sql, args.at(0)) sql << SPACE << op.to_s << SPACE literal_append(sql, args.at(1)) sql << ESCAPE literal_append(sql, BACKSLASH) sql << PAREN_CLOSE when :ILIKE, :'NOT ILIKE' complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)}) when *TWO_ARITY_OPERATORS if REGEXP_OPERATORS.include?(op) && !supports_regexp? raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}" end sql << PAREN_OPEN literal_append(sql, args.at(0)) sql << SPACE << op.to_s << SPACE literal_append(sql, args.at(1)) sql << PAREN_CLOSE when *N_ARITY_OPERATORS sql << PAREN_OPEN c = false op_str = " #{op} " args.each do |a| sql << op_str if c literal_append(sql, a) c ||= true end sql << PAREN_CLOSE when :NOT sql << NOT_SPACE literal_append(sql, args.at(0)) when :NOOP literal_append(sql, args.at(0)) when :'B~' sql << TILDE literal_append(sql, args.at(0)) when :extract sql << EXTRACT << args.at(0).to_s << FROM literal_append(sql, args.at(1)) sql << PAREN_CLOSE else raise(InvalidOperation, "invalid operator #{op}") end end |
#constant_sql_append(sql, constant) ⇒ Object
SQL fragment for constants
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# File 'lib/sequel/dataset/sql.rb', line 463 def constant_sql_append(sql, constant) sql << constant.to_s end |
#count(arg = (no_arg=true), &block) ⇒ Object
Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.
DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1
# => 3
DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1
# => 2
DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1
# => 1
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# File 'lib/sequel/dataset/actions.rb', line 101 def count(arg=(no_arg=true), &block) if no_arg if block arg = Sequel.virtual_row(&block) aggregate_dataset.get{count(arg).as(count)} else aggregate_dataset.get{count(:*){}.as(count)}.to_i end elsif block raise Error, 'cannot provide both argument and block to Dataset#count' else aggregate_dataset.get{count(arg).as(count)} end end |
#delayed_evaluation_sql_append(sql, callable) ⇒ Object
SQL fragment for delayed evaluations, evaluating the object and literalizing the returned value.
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# File 'lib/sequel/dataset/sql.rb', line 469 def delayed_evaluation_sql_append(sql, callable) literal_append(sql, callable.call) end |
#delete(&block) ⇒ Object
Deletes the records in the dataset. The returned value should be number of records deleted, but that is adapter dependent.
DB[:table].delete # DELETE * FROM table
# => 3
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# File 'lib/sequel/dataset/actions.rb', line 121 def delete(&block) sql = delete_sql if uses_returning?(:delete) returning_fetch_rows(sql, &block) else execute_dui(sql) end end |
#delete_sql ⇒ Object
Returns a DELETE SQL query string. See delete
.
dataset.filter{|o| o.price >= 100}.delete_sql
# => "DELETE FROM items WHERE (price >= 100)"
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# File 'lib/sequel/dataset/sql.rb', line 12 def delete_sql return static_sql(opts[:sql]) if opts[:sql] check_modification_allowed! clause_sql(:delete) end |
#distinct(*args) ⇒ Object
Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. Raises an error if arguments are given and DISTINCT ON is not supported.
DB[:items].distinct # SQL: SELECT DISTINCT * FROM items
DB[:items].order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
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# File 'lib/sequel/dataset/query.rb', line 95 def distinct(*args) raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on? clone(:distinct => args) end |
#dup ⇒ Object
Similar to #clone, but returns an unfrozen clone if the receiver is frozen.
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# File 'lib/sequel/dataset/misc.rb', line 45 def dup o = clone o.opts.delete(:frozen) o end |
#each ⇒ Object
Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.
DB[:table].each{|row| p row} # SELECT * FROM table
Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all
instead of each
for the outer queries, or use a separate thread or shard inside each
.
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# File 'lib/sequel/dataset/actions.rb', line 139 def each if row_proc = @row_proc fetch_rows(select_sql){|r| yield row_proc.call(r)} else fetch_rows(select_sql){|r| yield r} end self end |
#each_server ⇒ Object
Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:
DB[:configs].where(:key=>'setting').each_server{|ds| ds.update(:value=>'new_value')}
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# File 'lib/sequel/dataset/misc.rb', line 56 def each_server db.servers.each{|s| yield server(s)} end |
#empty? ⇒ Boolean
Returns true if no records exist in the dataset, false otherwise
DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
# => false
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# File 'lib/sequel/dataset/actions.rb', line 152 def empty? get(Sequel::SQL::AliasedExpression.new(1, :one)).nil? end |
#emulated_function_sql_append(sql, f) ⇒ Object
SQL fragment specifying an emulated SQL function call. By default, assumes just the function name may need to be emulated, adapters should set an EMULATED_FUNCTION_MAP hash mapping emulated functions to native functions in their dataset class to setup the emulation.
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# File 'lib/sequel/dataset/sql.rb', line 478 def emulated_function_sql_append(sql, f) _function_sql_append(sql, native_function_name(f.f), f.args) end |
#eql?(o) ⇒ Boolean
Alias for ==
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# File 'lib/sequel/dataset/misc.rb', line 40 def eql?(o) self == o end |
#escape_like(string) ⇒ Object
Returns the string with the LIKE metacharacters (% and _) escaped. Useful for when the LIKE term is a user-provided string where metacharacters should not be recognized. Example:
ds.escape_like("foo\\%_") # 'foo\\\%\_'
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# File 'lib/sequel/dataset/misc.rb', line 65 def escape_like(string) string.gsub(/[\\%_]/){|m| "\\#{m}"} end |
#except(dataset, opts = OPTS) ⇒ Object
Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation
if the operation is not supported. Options:
- :alias
-
Use the given value as the from_self alias
- :all
-
Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur
- :from_self
-
Set to false to not wrap the returned dataset in a from_self, use with care.
DB[:items].except(DB[:other_items])
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1
DB[:items].except(DB[:other_items], :all=>true, :from_self=>false)
# SELECT * FROM items EXCEPT ALL SELECT * FROM other_items
DB[:items].except(DB[:other_items], :alias=>:i)
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
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# File 'lib/sequel/dataset/query.rb', line 117 def except(dataset, opts=OPTS) raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except? raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all? compound_clone(:except, dataset, opts) end |
#exclude(*cond, &block) ⇒ Object
Performs the inverse of Dataset#where. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.
DB[:items].exclude(:category => 'software')
# SELECT * FROM items WHERE (category != 'software')
DB[:items].exclude(:category => 'software', :id=>3)
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
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# File 'lib/sequel/dataset/query.rb', line 131 def exclude(*cond, &block) _filter_or_exclude(true, :where, *cond, &block) end |
#exclude_having(*cond, &block) ⇒ Object
Inverts the given conditions and adds them to the HAVING clause.
DB[:items].select_group(:name).exclude_having{count(name) < 2}
# SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)
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# File 'lib/sequel/dataset/query.rb', line 139 def exclude_having(*cond, &block) _filter_or_exclude(true, :having, *cond, &block) end |
#exclude_where(*cond, &block) ⇒ Object
Alias for exclude.
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# File 'lib/sequel/dataset/query.rb', line 144 def exclude_where(*cond, &block) exclude(*cond, &block) end |
#exists ⇒ Object
Returns an EXISTS clause for the dataset as a LiteralString
.
DB.select(1).where(DB[:items].exists)
# SELECT 1 WHERE (EXISTS (SELECT * FROM items))
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# File 'lib/sequel/dataset/sql.rb', line 22 def exists SQL::PlaceholderLiteralString.new(EXISTS, [self], true) end |
#extension(*exts) ⇒ Object
Return a clone of the dataset loaded with the extensions, see #extension!.
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# File 'lib/sequel/dataset/query.rb', line 149 def extension(*exts) clone.extension!(*exts) end |
#extension!(*exts) ⇒ Object
Load an extension into the receiver. In addition to requiring the extension file, this also modifies the dataset to work with the extension (usually extending it with a module defined in the extension file). If no related extension file exists or the extension does not have specific support for Database objects, an Error will be raised. Returns self.
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# File 'lib/sequel/dataset/mutation.rb', line 38 def extension!(*exts) raise_if_frozen! Sequel.extension(*exts) exts.each do |ext| if pr = Sequel.synchronize{EXTENSIONS[ext]} pr.call(self) else raise(Error, "Extension #{ext} does not have specific support handling individual datasets") end end self end |
#filter(*cond, &block) ⇒ Object
Alias for where.
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# File 'lib/sequel/dataset/query.rb', line 154 def filter(*cond, &block) where(*cond, &block) end |
#first(*args, &block) ⇒ Object
If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If no argument is passed, it returns the first matching record. If any other type of argument(s) is passed, it is given to filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything.
If there are no records in the dataset, returns nil (or an empty array if an integer argument is given).
Examples:
DB[:table].first # SELECT * FROM table LIMIT 1
# => {:id=>7}
DB[:table].first(2) # SELECT * FROM table LIMIT 2
# => [{:id=>6}, {:id=>4}]
DB[:table].first(:id=>2) # SELECT * FROM table WHERE (id = 2) LIMIT 1
# => {:id=>2}
DB[:table].first("id = 3") # SELECT * FROM table WHERE (id = 3) LIMIT 1
# => {:id=>3}
DB[:table].first("id = ?", 4) # SELECT * FROM table WHERE (id = 4) LIMIT 1
# => {:id=>4}
DB[:table].first{id > 2} # SELECT * FROM table WHERE (id > 2) LIMIT 1
# => {:id=>5}
DB[:table].first("id > ?", 4){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1
# => {:id=>5}
DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2
# => [{:id=>1}]
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# File 'lib/sequel/dataset/actions.rb', line 191 def first(*args, &block) ds = block ? filter(&block) : self if args.empty? ds.single_record else args = (args.size == 1) ? args.first : args if args.is_a?(Integer) ds.limit(args).all else ds.filter(args).single_record end end end |
#first!(*args, &block) ⇒ Object
Calls first. If first returns nil (signaling that no row matches), raise a Sequel::NoMatchingRow exception.
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# File 'lib/sequel/dataset/actions.rb', line 208 def first!(*args, &block) first(*args, &block) || raise(Sequel::NoMatchingRow) end |
#first_source ⇒ Object
Alias of first_source_alias
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# File 'lib/sequel/dataset/misc.rb', line 81 def first_source first_source_alias end |
#first_source_alias ⇒ Object
The first source (primary table) for this dataset. If the dataset doesn’t have a table, raises an Error
. If the table is aliased, returns the aliased name.
DB[:table].first_source_alias
# => :table
DB[:table___t].first_source_alias
# => :t
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# File 'lib/sequel/dataset/misc.rb', line 93 def first_source_alias source = @opts[:from] if source.nil? || source.empty? raise Error, 'No source specified for query' end case s = source.first when SQL::AliasedExpression s.aliaz when Symbol _, _, aliaz = split_symbol(s) aliaz ? aliaz.to_sym : s else s end end |
#first_source_table ⇒ Object
The first source (primary table) for this dataset. If the dataset doesn’t have a table, raises an error. If the table is aliased, returns the original table, not the alias
DB[:table].first_source_table
# => :table
DB[:table___t].first_source_table
# => :table
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# File 'lib/sequel/dataset/misc.rb', line 118 def first_source_table source = @opts[:from] if source.nil? || source.empty? raise Error, 'No source specified for query' end case s = source.first when SQL::AliasedExpression s.expression when Symbol sch, table, aliaz = split_symbol(s) aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s else s end end |
#for_update ⇒ Object
Returns a cloned dataset with a :update lock style.
DB[:table].for_update # SELECT * FROM table FOR UPDATE
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# File 'lib/sequel/dataset/query.rb', line 161 def for_update lock_style(:update) end |
#freeze ⇒ Object
Sets the frozen flag on the dataset, so you can’t modify it. Returns the receiver.
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# File 'lib/sequel/dataset/misc.rb', line 70 def freeze @opts[:frozen] = true self end |
#from(*source, &block) ⇒ Object
Returns a copy of the dataset with the source changed. If no source is given, removes all tables. If multiple sources are given, it is the same as using a CROSS JOIN (cartesian product) between all tables. If a block is given, it is treated as a virtual row block, similar to where
.
DB[:items].from # SQL: SELECT *
DB[:items].from(:blah) # SQL: SELECT * FROM blah
DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo
DB[:items].from{fun(arg)} # SQL: SELECT * FROM fun(arg)
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# File 'lib/sequel/dataset/query.rb', line 174 def from(*source, &block) virtual_row_columns(source, block) table_alias_num = 0 ctes = nil source.map! do |s| case s when Dataset if hoist_cte?(s) ctes ||= [] ctes += s.opts[:with] s = s.clone(:with=>nil) end SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1)) when Symbol sch, table, aliaz = split_symbol(s) if aliaz s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table) SQL::AliasedExpression.new(s, aliaz.to_sym) else s end else s end end o = {:from=>source.empty? ? nil : source} o[:with] = (opts[:with] || []) + ctes if ctes o[:num_dataset_sources] = table_alias_num if table_alias_num > 0 clone(o) end |
#from_self(opts = OPTS) ⇒ Object
Returns a dataset selecting from the current dataset. Supplying the :alias option controls the alias of the result.
ds = DB[:items].order(:name).select(:id, :name)
# SELECT id,name FROM items ORDER BY name
ds.from_self
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1
ds.from_self(:alias=>:foo)
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo
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# File 'lib/sequel/dataset/query.rb', line 216 def from_self(opts=OPTS) fs = {} @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)} clone(fs).from(opts[:alias] ? as(opts[:alias]) : self) end |
#from_self!(*args, &block) ⇒ Object
Avoid self-referential dataset by cloning.
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# File 'lib/sequel/dataset/mutation.rb', line 52 def from_self!(*args, &block) raise_if_frozen! @opts = clone.from_self(*args, &block).opts self end |
#frozen? ⇒ Boolean
Whether the object is frozen.
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# File 'lib/sequel/dataset/misc.rb', line 76 def frozen? @opts[:frozen] end |
#function_sql_append(sql, f) ⇒ Object
SQL fragment specifying an SQL function call without emulation.
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# File 'lib/sequel/dataset/sql.rb', line 483 def function_sql_append(sql, f) _function_sql_append(sql, f.f, f.args) end |
#get(column = (no_arg=true; nil), &block) ⇒ Object
Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.
DB[:table].get(:id) # SELECT id FROM table LIMIT 1
# => 3
ds.get{sum(id)} # SELECT sum(id) AS v FROM table LIMIT 1
# => 6
You can pass an array of arguments to return multiple arguments, but you must make sure each element in the array has an alias that Sequel can determine:
DB[:table].get([:id, :name]) # SELECT id, name FROM table LIMIT 1
# => [3, 'foo']
DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1
# => [6, 'foo']
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# File 'lib/sequel/dataset/actions.rb', line 230 def get(column=(no_arg=true; nil), &block) ds = naked if block raise(Error, ARG_BLOCK_ERROR_MSG) unless no_arg ds = ds.select(&block) column = ds.opts[:select] column = nil if column.is_a?(Array) && column.length < 2 else ds = if column.is_a?(Array) ds.select(*column) else ds.select(auto_alias_expression(column)) end end if column.is_a?(Array) if r = ds.single_record r.values_at(*hash_key_symbols(column)) end else ds.single_value end end |
#graph(dataset, join_conditions = nil, options = OPTS, &block) ⇒ Object
Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.
Arguments:
- dataset
-
Can be a symbol (specifying a table), another dataset, or an object that responds to
dataset
and returns a symbol or a dataset - join_conditions
-
Any condition(s) allowed by
join_table
. - block
-
A block that is passed to
join_table
.
Options:
- :from_self_alias
-
The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use.
- :implicit_qualifier
-
The qualifier of implicit conditions, see #join_table.
- :join_type
-
The type of join to use (passed to
join_table
). Defaults to :left_outer. - :qualify
-
The type of qualification to do, see #join_table.
- :select
-
An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use
graph
instead ofjoin_table
. - :table_alias
-
The alias to use for the table. If not specified, doesn’t alias the table. You will get an error if the the alias (or table) name is used more than once.
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# File 'lib/sequel/dataset/graph.rb', line 49 def graph(dataset, join_conditions = nil, = OPTS, &block) # Allow the use of a dataset or symbol as the first argument # Find the table name/dataset based on the argument table_alias = [:table_alias] case dataset when Symbol table = dataset dataset = @db[dataset] table_alias ||= table when ::Sequel::Dataset if dataset.simple_select_all? table = dataset.opts[:from].first table_alias ||= table else table = dataset table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1) end else raise Error, "The dataset argument should be a symbol or dataset" end # Raise Sequel::Error with explanation that the table alias has been used raise_alias_error = lambda do raise(Error, "this #{[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \ "#{[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") end # Only allow table aliases that haven't been used raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias) # Use a from_self if this is already a joined table ds = (!@opts[:graph] && (@opts[:from].length > 1 || @opts[:join])) ? from_self(:alias=>[:from_self_alias] || first_source) : self # Join the table early in order to avoid cloning the dataset twice ds = ds.join_table([:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>[:implicit_qualifier], :qualify=>[:qualify], &block) opts = ds.opts # Whether to include the table in the result set add_table = [:select] == false ? false : true # Whether to add the columns to the list of column aliases add_columns = !ds.opts.include?(:graph_aliases) # Setup the initial graph data structure if it doesn't exist if graph = opts[:graph] opts[:graph] = graph = graph.dup select = opts[:select].dup [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup} else master = alias_symbol(ds.first_source_alias) raise_alias_error.call if master == table_alias # Master hash storing all .graph related information graph = opts[:graph] = {} # Associates column aliases back to tables and columns column_aliases = graph[:column_aliases] = {} # Associates table alias (the master is never aliased) table_aliases = graph[:table_aliases] = {master=>self} # Keep track of the alias numbers used ca_num = graph[:column_alias_num] = Hash.new(0) # All columns in the master table are never # aliased, but are not included if set_graph_aliases # has been used. if add_columns if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll))) select = select.each do |sel| column = case sel when Symbol _, c, a = split_symbol(sel) (a || c).to_sym when SQL::Identifier sel.value.to_sym when SQL::QualifiedIdentifier column = sel.column column = column.value if column.is_a?(SQL::Identifier) column.to_sym when SQL::AliasedExpression column = sel.aliaz column = column.value if column.is_a?(SQL::Identifier) column.to_sym else raise Error, "can't figure out alias to use for graphing for #{sel.inspect}" end column_aliases[column] = [master, column] end select = qualified_expression(select, master) else select = columns.map do |column| column_aliases[column] = [master, column] SQL::QualifiedIdentifier.new(master, column) end end end end # Add the table alias to the list of aliases # Even if it isn't been used in the result set, # we add a key for it with a nil value so we can check if it # is used more than once table_aliases = graph[:table_aliases] table_aliases[table_alias] = add_table ? dataset : nil # Add the columns to the selection unless we are ignoring them if add_table && add_columns column_aliases = graph[:column_aliases] ca_num = graph[:column_alias_num] # Which columns to add to the result set cols = [:select] || dataset.columns # If the column hasn't been used yet, don't alias it. # If it has been used, try table_column. # If that has been used, try table_column_N # using the next value of N that we know hasn't been # used cols.each do |column| col_alias, identifier = if column_aliases[column] column_alias = :"#{table_alias}_#{column}" if column_aliases[column_alias] column_alias_num = ca_num[column_alias] column_alias = :"#{column_alias}_#{column_alias_num}" ca_num[column_alias] += 1 end [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias, column), column_alias)] else ident = SQL::QualifiedIdentifier.new(table_alias, column) [column, ident] end column_aliases[col_alias] = [table_alias, column] select.push(identifier) end end add_columns ? ds.select(*select) : ds end |
#grep(columns, patterns, opts = OPTS) ⇒ Object
Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions (which are only supported on MySQL and PostgreSQL). Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.
Options (all are boolean):
- :all_columns
-
All columns must be matched to any of the given patterns.
- :all_patterns
-
All patterns must match at least one of the columns.
- :case_insensitive
-
Use a case insensitive pattern match (the default is case sensitive if the database supports it).
If both :all_columns and :all_patterns are true, all columns must match all patterns.
Examples:
dataset.grep(:a, '%test%')
# SELECT * FROM items WHERE (a LIKE '%test%')
dataset.grep([:a, :b], %w'%test% foo')
# SELECT * FROM items WHERE ((a LIKE '%test%') OR (a LIKE 'foo') OR (b LIKE '%test%') OR (b LIKE 'foo'))
dataset.grep([:a, :b], %w'%foo% %bar%', :all_patterns=>true)
# SELECT * FROM a WHERE (((a LIKE '%foo%') OR (b LIKE '%foo%')) AND ((a LIKE '%bar%') OR (b LIKE '%bar%')))
dataset.grep([:a, :b], %w'%foo% %bar%', :all_columns=>true)
# SELECT * FROM a WHERE (((a LIKE '%foo%') OR (a LIKE '%bar%')) AND ((b LIKE '%foo%') OR (b LIKE '%bar%')))
dataset.grep([:a, :b], %w'%foo% %bar%', :all_patterns=>true, :all_columns=>true)
# SELECT * FROM a WHERE ((a LIKE '%foo%') AND (b LIKE '%foo%') AND (a LIKE '%bar%') AND (b LIKE '%bar%'))
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# File 'lib/sequel/dataset/query.rb', line 253 def grep(columns, patterns, opts=OPTS) if opts[:all_patterns] conds = Array(patterns).map do |pat| SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)}) end where(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds)) else conds = Array(columns).map do |c| SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)}) end where(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds)) end end |
#group(*columns, &block) ⇒ Object
Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to where
.
DB[:items].group(:id) # SELECT * FROM items GROUP BY id
DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name
DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
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# File 'lib/sequel/dataset/query.rb', line 274 def group(*columns, &block) virtual_row_columns(columns, block) clone(:group => (columns.compact.empty? ? nil : columns)) end |
#group_and_count(*columns, &block) ⇒ Object
Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to where
.
Examples:
DB[:items].group_and_count(:name).all
# SELECT name, count(*) AS count FROM items GROUP BY name
# => [{:name=>'a', :count=>1}, ...]
DB[:items].group_and_count(:first_name, :last_name).all
# SELECT first_name, last_name, count(*) AS count FROM items GROUP BY first_name, last_name
# => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]
DB[:items].group_and_count(:first_name___name).all
# SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name
# => [{:name=>'a', :count=>1}, ...]
DB[:items].group_and_count{substr(first_name, 1, 1).as(initial)}.all
# SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1)
# => [{:initial=>'a', :count=>1}, ...]
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# File 'lib/sequel/dataset/query.rb', line 305 def group_and_count(*columns, &block) select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT) end |
#group_by(*columns, &block) ⇒ Object
Alias of group
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# File 'lib/sequel/dataset/query.rb', line 280 def group_by(*columns, &block) group(*columns, &block) end |
#group_cube ⇒ Object
Adds the appropriate CUBE syntax to GROUP BY.
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# File 'lib/sequel/dataset/query.rb', line 310 def group_cube raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube? clone(:group_options=>:cube) end |
#group_rollup ⇒ Object
Adds the appropriate ROLLUP syntax to GROUP BY.
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# File 'lib/sequel/dataset/query.rb', line 316 def group_rollup raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup? clone(:group_options=>:rollup) end |
#hash ⇒ Object
Define a hash value such that datasets with the same DB, opts, and SQL will have the same hash value
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# File 'lib/sequel/dataset/misc.rb', line 136 def hash [db, opts, sql].hash end |
#having(*cond, &block) ⇒ Object
Returns a copy of the dataset with the HAVING conditions changed. See #where for argument types.
DB[:items].group(:sum).having(:sum=>10)
# SELECT * FROM items GROUP BY sum HAVING (sum = 10)
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# File 'lib/sequel/dataset/query.rb', line 325 def having(*cond, &block) _filter(:having, *cond, &block) end |
#identifier_input_method ⇒ Object
The String instance method to call on identifiers before sending them to the database.
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# File 'lib/sequel/dataset/misc.rb', line 142 def identifier_input_method if defined?(@identifier_input_method) @identifier_input_method else @identifier_input_method = db.identifier_input_method end end |
#identifier_input_method=(v) ⇒ Object
Set the method to call on identifiers going into the database for this dataset
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# File 'lib/sequel/dataset/mutation.rb', line 59 def identifier_input_method=(v) raise_if_frozen! @identifier_input_method = v end |
#identifier_output_method ⇒ Object
The String instance method to call on identifiers before sending them to the database.
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# File 'lib/sequel/dataset/misc.rb', line 152 def identifier_output_method if defined?(@identifier_output_method) @identifier_output_method else @identifier_output_method = db.identifier_output_method end end |
#identifier_output_method=(v) ⇒ Object
Set the method to call on identifiers coming the database for this dataset
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# File 'lib/sequel/dataset/mutation.rb', line 65 def identifier_output_method=(v) raise_if_frozen! @identifier_output_method = v end |
#import(columns, values, opts = OPTS) ⇒ Object
Inserts multiple records into the associated table. This method can be used to efficiently insert a large number of records into a table in a single query if the database supports it. Inserts are automatically wrapped in a transaction.
This method is called with a columns array and an array of value arrays:
DB[:table].import([:x, :y], [[1, 2], [3, 4]])
# INSERT INTO table (x, y) VALUES (1, 2)
# INSERT INTO table (x, y) VALUES (3, 4)
This method also accepts a dataset instead of an array of value arrays:
DB[:table].import([:x, :y], DB[:table2].select(:a, :b))
# INSERT INTO table (x, y) SELECT a, b FROM table2
Options:
- :commit_every
-
Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records.
- :server
-
Set the server/shard to use for the transaction and insert queries.
- :slice
-
Same as :commit_every, :commit_every takes precedence.
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# File 'lib/sequel/dataset/actions.rb', line 277 def import(columns, values, opts=OPTS) return @db.transaction{insert(columns, values)} if values.is_a?(Dataset) return if values.empty? raise(Error, IMPORT_ERROR_MSG) if columns.empty? ds = opts[:server] ? server(opts[:server]) : self if slice_size = opts[:commit_every] || opts[:slice] offset = 0 rows = [] while offset < values.length rows << ds._import(columns, values[offset, slice_size], opts) offset += slice_size end rows.flatten else ds._import(columns, values, opts) end end |
#insert(*values, &block) ⇒ Object
Inserts values into the associated table. The returned value is generally the value of the primary key for the inserted row, but that is adapter dependent.
insert
handles a number of different argument formats:
- no arguments or single empty hash
-
Uses DEFAULT VALUES
- single hash
-
Most common format, treats keys as columns an values as values
- single array
-
Treats entries as values, with no columns
- two arrays
-
Treats first array as columns, second array as values
- single Dataset
-
Treats as an insert based on a selection from the dataset given, with no columns
- array and dataset
-
Treats as an insert based on a selection from the dataset given, with the columns given by the array.
Examples:
DB[:items].insert
# INSERT INTO items DEFAULT VALUES
DB[:items].insert({})
# INSERT INTO items DEFAULT VALUES
DB[:items].insert([1,2,3])
# INSERT INTO items VALUES (1, 2, 3)
DB[:items].insert([:a, :b], [1,2])
# INSERT INTO items (a, b) VALUES (1, 2)
DB[:items].insert(:a => 1, :b => 2)
# INSERT INTO items (a, b) VALUES (1, 2)
DB[:items].insert(DB[:old_items])
# INSERT INTO items SELECT * FROM old_items
DB[:items].insert([:a, :b], DB[:old_items])
# INSERT INTO items (a, b) SELECT * FROM old_items
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# File 'lib/sequel/dataset/actions.rb', line 332 def insert(*values, &block) sql = insert_sql(*values) if uses_returning?(:insert) returning_fetch_rows(sql, &block) else execute_insert(sql) end end |
#insert_sql(*values) ⇒ Object
Returns an INSERT SQL query string. See insert
.
DB[:items].insert_sql(:a=>1)
# => "INSERT INTO items (a) VALUES (1)"
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# File 'lib/sequel/dataset/sql.rb', line 30 def insert_sql(*values) return static_sql(@opts[:sql]) if @opts[:sql] check_modification_allowed! columns = [] case values.size when 0 return insert_sql({}) when 1 case vals = values.at(0) when Hash values = [] vals.each do |k,v| columns << k values << v end when Dataset, Array, LiteralString values = vals end when 2 if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString)) columns, values = v0, v1 raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length end end if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? columns = [columns().last] values = [DEFAULT] end clone(:columns=>columns, :values=>values)._insert_sql end |
#inspect ⇒ Object
Returns a string representation of the dataset including the class name and the corresponding SQL select statement.
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# File 'lib/sequel/dataset/misc.rb', line 162 def inspect "#<#{visible_class_name}: #{sql.inspect}>" end |
#intersect(dataset, opts = OPTS) ⇒ Object
Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation
if the operation is not supported. Options:
- :alias
-
Use the given value as the from_self alias
- :all
-
Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur
- :from_self
-
Set to false to not wrap the returned dataset in a from_self, use with care.
DB[:items].intersect(DB[:other_items])
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1
DB[:items].intersect(DB[:other_items], :all=>true, :from_self=>false)
# SELECT * FROM items INTERSECT ALL SELECT * FROM other_items
DB[:items].intersect(DB[:other_items], :alias=>:i)
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
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# File 'lib/sequel/dataset/query.rb', line 346 def intersect(dataset, opts=OPTS) raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except? raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all? compound_clone(:intersect, dataset, opts) end |
#interval(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the interval between minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].interval(:id) # SELECT (max(id) - min(id)) FROM table LIMIT 1
# => 6
DB[:table].interval{function(column)} # SELECT (max(function(column)) - min(function(column))) FROM table LIMIT 1
# => 7
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# File 'lib/sequel/dataset/actions.rb', line 348 def interval(column=Sequel.virtual_row(&Proc.new)) aggregate_dataset.get{(max(column) - min(column)).as(:interval)} end |
#invert ⇒ Object
Inverts the current WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.
DB[:items].where(:category => 'software').invert
# SELECT * FROM items WHERE (category != 'software')
DB[:items].where(:category => 'software', :id=>3).invert
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
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# File 'lib/sequel/dataset/query.rb', line 360 def invert having, where = @opts.values_at(:having, :where) if having.nil? && where.nil? where(false) else o = {} o[:having] = SQL::BooleanExpression.invert(having) if having o[:where] = SQL::BooleanExpression.invert(where) if where clone(o) end end |
#join(*args, &block) ⇒ Object
Alias of inner_join
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# File 'lib/sequel/dataset/query.rb', line 373 def join(*args, &block) inner_join(*args, &block) end |
#join_clause_sql_append(sql, jc) ⇒ Object
SQL fragment specifying a JOIN clause without ON or USING.
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# File 'lib/sequel/dataset/sql.rb', line 488 def join_clause_sql_append(sql, jc) table = jc.table table_alias = jc.table_alias table_alias = nil if table == table_alias sql << SPACE << join_type_sql(jc.join_type) << SPACE identifier_append(sql, table) as_sql_append(sql, table_alias) if table_alias end |
#join_on_clause_sql_append(sql, jc) ⇒ Object
SQL fragment specifying a JOIN clause with ON.
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# File 'lib/sequel/dataset/sql.rb', line 498 def join_on_clause_sql_append(sql, jc) join_clause_sql_append(sql, jc) sql << ON literal_append(sql, filter_expr(jc.on)) end |
#join_table(type, table, expr = nil, options = OPTS, &block) ⇒ Object
Returns a joined dataset. Not usually called directly, users should use the appropriate join method (e.g. join, left_join, natural_join, cross_join) which fills in the type
argument.
Takes the following arguments:
-
type - The type of join to do (e.g. :inner)
-
table - Depends on type:
-
Dataset - a subselect is performed with an alias of tN for some value of N
-
String, Symbol: table
-
-
expr - specifies conditions, depends on type:
-
Hash, Array of two element arrays - Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.
-
Array - If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.
-
nil - If a block is not given, doesn’t use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses an ON clause based on the block, see below.
-
Everything else - pretty much the same as a using the argument in a call to where, so strings are considered literal, symbols specify boolean columns, and Sequel expressions can be used. Uses a JOIN with an ON clause.
-
-
options - a hash of options, with any of the following keys:
-
:table_alias - the name of the table’s alias when joining, necessary for joining to the same table more than once. No alias is used by default.
-
:implicit_qualifier - The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.
-
:qualify - Can be set to false to not do any implicit qualification. Can be set to :deep to use the Qualifier AST Transformer, which will attempt to qualify subexpressions of the expression tree. Can be set to :symbol to only qualify symbols. Defaults to the value of default_join_table_qualification.
-
-
block - The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause. Unlike
where
, this block is not treated as a virtual row block.
Examples:
DB[:a].join_table(:cross, :b)
# SELECT * FROM a CROSS JOIN b
DB[:a].join_table(:inner, DB[:b], :c=>d)
# SELECT * FROM a INNER JOIN (SELECT * FROM b) AS t1 ON (t1.c = a.d)
DB[:a].join_table(:left, :b___c, [:d])
# SELECT * FROM a LEFT JOIN b AS c USING (d)
DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js|
(Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)}
end
# SELECT * FROM a NATURAL JOIN b INNER JOIN c
# ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
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# File 'lib/sequel/dataset/query.rb', line 431 def join_table(type, table, expr=nil, =OPTS, &block) if hoist_cte?(table) s, ds = hoist_cte(table) return s.join_table(type, ds, expr, , &block) end using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)} if using_join && !supports_join_using? h = {} expr.each{|e| h[e] = e} return join_table(type, table, h, ) end table_alias = [:table_alias] last_alias = [:implicit_qualifier] qualify_type = [:qualify] if table.is_a?(Dataset) if table_alias.nil? table_alias_num = (@opts[:num_dataset_sources] || 0) + 1 table_alias = dataset_alias(table_alias_num) end table_name = table_alias else table, implicit_table_alias = split_alias(table) table_alias ||= implicit_table_alias table_name = table_alias || table end join = if expr.nil? and !block SQL::JoinClause.new(type, table, table_alias) elsif using_join raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block SQL::JoinUsingClause.new(expr, type, table, table_alias) else last_alias ||= @opts[:last_joined_table] || first_source_alias if Sequel.condition_specifier?(expr) expr = expr.collect do |k, v| qualify_type = default_join_table_qualification if qualify_type.nil? case qualify_type when false nil # Do no qualification when :deep k = Sequel::Qualifier.new(self, table_name).transform(k) v = Sequel::Qualifier.new(self, last_alias).transform(v) else k = qualified_column_name(k, table_name) if k.is_a?(Symbol) v = qualified_column_name(v, last_alias) if v.is_a?(Symbol) end [k,v] end expr = SQL::BooleanExpression.from_value_pairs(expr) end if block expr2 = yield(table_name, last_alias, @opts[:join] || []) expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2 end SQL::JoinOnClause.new(expr, type, table, table_alias) end opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name} opts[:num_dataset_sources] = table_alias_num if table_alias_num clone(opts) end |
#join_using_clause_sql_append(sql, jc) ⇒ Object
SQL fragment specifying a JOIN clause with USING.
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# File 'lib/sequel/dataset/sql.rb', line 505 def join_using_clause_sql_append(sql, jc) join_clause_sql_append(sql, jc) sql << USING column_list_append(sql, jc.using) sql << PAREN_CLOSE end |
#last(*args, &block) ⇒ Object
Reverses the order and then runs #first with the given arguments and block. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error
.
DB[:table].order(:id).last # SELECT * FROM table ORDER BY id DESC LIMIT 1
# => {:id=>10}
DB[:table].order(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
# => [{:id=>1}, {:id=>2}]
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# File 'lib/sequel/dataset/actions.rb', line 362 def last(*args, &block) raise(Error, 'No order specified') unless @opts[:order] reverse.first(*args, &block) end |
#lateral ⇒ Object
Marks this dataset as a lateral dataset. If used in another dataset’s FROM or JOIN clauses, it will surround the subquery with LATERAL to enable it to deal with previous tables in the query:
DB.from(:a, DB[:b].where(:a__c=>:b__d).lateral)
# SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))
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# File 'lib/sequel/dataset/query.rb', line 509 def lateral clone(:lateral=>true) end |
#limit(l, o = (no_offset = true; nil)) ⇒ Object
If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.
DB[:items].limit(10) # SELECT * FROM items LIMIT 10
DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20
DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10
DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10
DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
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# File 'lib/sequel/dataset/query.rb', line 523 def limit(l, o = (no_offset = true; nil)) return from_self.limit(l, o) if @opts[:sql] if l.is_a?(Range) o = l.first l = l.last - l.first + (l.exclude_end? ? 0 : 1) end l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString) if l.is_a?(Integer) raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1 end opts = {:limit => l} if o o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString) if o.is_a?(Integer) raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0 end opts[:offset] = o elsif !no_offset opts[:offset] = nil end clone(opts) end |
#literal_append(sql, v) ⇒ Object
Returns a literal representation of a value to be used as part of an SQL expression.
DB[:items].literal("abc'def\\") #=> "'abc''def\\\\'"
DB[:items].literal(:items__id) #=> "items.id"
DB[:items].literal([1, 2, 3]) => "(1, 2, 3)"
DB[:items].literal(DB[:items]) => "(SELECT * FROM items)"
DB[:items].literal(:x + 1 > :y) => "((x + 1) > y)"
If an unsupported object is given, an Error
is raised.
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# File 'lib/sequel/dataset/sql.rb', line 75 def literal_append(sql, v) case v when Symbol literal_symbol_append(sql, v) when String case v when LiteralString sql << v when SQL::Blob literal_blob_append(sql, v) else literal_string_append(sql, v) end when Integer sql << literal_integer(v) when Hash literal_hash_append(sql, v) when SQL::Expression literal_expression_append(sql, v) when Float sql << literal_float(v) when BigDecimal sql << literal_big_decimal(v) when NilClass sql << literal_nil when TrueClass sql << literal_true when FalseClass sql << literal_false when Array literal_array_append(sql, v) when Time sql << (v.is_a?(SQLTime) ? literal_sqltime(v) : literal_time(v)) when DateTime sql << literal_datetime(v) when Date sql << literal_date(v) when Dataset literal_dataset_append(sql, v) else literal_other_append(sql, v) end end |
#lock_style(style) ⇒ Object
Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. You should never pass a string to this method that is derived from user input, as that can lead to SQL injection.
A symbol may be used for database independent locking behavior, but all supported symbols have separate methods (e.g. for_update).
DB[:items].lock_style('FOR SHARE NOWAIT') # SELECT * FROM items FOR SHARE NOWAIT
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# File 'lib/sequel/dataset/query.rb', line 556 def lock_style(style) clone(:lock => style) end |
#map(column = nil, &block) ⇒ Object
Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable
otherwise. Raises an Error
if both an argument and block are given.
DB[:table].map(:id) # SELECT * FROM table
# => [1, 2, 3, ...]
DB[:table].map{|r| r[:id] * 2} # SELECT * FROM table
# => [2, 4, 6, ...]
You can also provide an array of column names:
DB[:table].map([:id, :name]) # SELECT * FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
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# File 'lib/sequel/dataset/actions.rb', line 381 def map(column=nil, &block) if column raise(Error, ARG_BLOCK_ERROR_MSG) if block return naked.map(column) if row_proc if column.is_a?(Array) super(){|r| r.values_at(*column)} else super(){|r| r[column]} end else super(&block) end end |
#max(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the maximum value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
# => 10
DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1
# => 7
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# File 'lib/sequel/dataset/actions.rb', line 402 def max(column=Sequel.virtual_row(&Proc.new)) aggregate_dataset.get{max(column).as(:max)} end |
#min(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the minimum value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1
# => 1
DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1
# => 0
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# File 'lib/sequel/dataset/actions.rb', line 413 def min(column=Sequel.virtual_row(&Proc.new)) aggregate_dataset.get{min(column).as(:min)} end |
#multi_insert(hashes, opts = OPTS) ⇒ Object
This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:
DB[:table].multi_insert([{:x => 1}, {:x => 2}])
# INSERT INTO table (x) VALUES (1)
# INSERT INTO table (x) VALUES (2)
Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.
This respects the same options as #import.
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# File 'lib/sequel/dataset/actions.rb', line 429 def multi_insert(hashes, opts=OPTS) return if hashes.empty? columns = hashes.first.keys import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts) end |
#multi_insert_sql(columns, values) ⇒ Object
Returns an array of insert statements for inserting multiple records. This method is used by multi_insert
to format insert statements and expects a keys array and and an array of value arrays.
This method should be overridden by descendants if the support inserting multiple records in a single SQL statement.
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# File 'lib/sequel/dataset/sql.rb', line 125 def multi_insert_sql(columns, values) values.map{|r| insert_sql(columns, r)} end |
#naked ⇒ Object
Returns a cloned dataset without a row_proc.
ds = DB[:items]
ds.row_proc = proc{|r| r.invert}
ds.all # => [{2=>:id}]
ds.naked.all # => [{:id=>2}]
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# File 'lib/sequel/dataset/query.rb', line 566 def naked ds = clone ds.row_proc = nil ds end |
#naked! ⇒ Object
Remove the row_proc from the current dataset.
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# File 'lib/sequel/dataset/mutation.rb', line 71 def naked! raise_if_frozen! self.row_proc = nil self end |
#negative_boolean_constant_sql_append(sql, constant) ⇒ Object
SQL fragment for NegativeBooleanConstants
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# File 'lib/sequel/dataset/sql.rb', line 513 def negative_boolean_constant_sql_append(sql, constant) sql << NOT_SPACE boolean_constant_sql_append(sql, constant) end |
#or(*cond, &block) ⇒ Object
Adds an alternate filter to an existing filter using OR. If no filter exists an Error
is raised.
DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b
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# File 'lib/sequel/dataset/query.rb', line 576 def or(*cond, &block) cond = cond.first if cond.size == 1 v = @opts[:where] if v.nil? || (cond.respond_to?(:empty?) && cond.empty? && !block) clone else clone(:where => SQL::BooleanExpression.new(:OR, v, filter_expr(cond, &block))) end end |
#order(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to where
.
DB[:items].order(:name) # SELECT * FROM items ORDER BY name
DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b
DB[:items].order(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b
DB[:items].order(:a + :b) # SELECT * FROM items ORDER BY (a + b)
DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC
DB[:items].order(Sequel.asc(:name, :nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
DB[:items].order(nil) # SELECT * FROM items
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# File 'lib/sequel/dataset/query.rb', line 600 def order(*columns, &block) virtual_row_columns(columns, block) clone(:order => (columns.compact.empty?) ? nil : columns) end |
#order_append(*columns, &block) ⇒ Object
Alias of order_more, for naming consistency with order_prepend.
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# File 'lib/sequel/dataset/query.rb', line 606 def order_append(*columns, &block) order_more(*columns, &block) end |
#order_by(*columns, &block) ⇒ Object
Alias of order
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# File 'lib/sequel/dataset/query.rb', line 611 def order_by(*columns, &block) order(*columns, &block) end |
#order_more(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order columns added to the end of the existing order.
DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_more(:b) # SELECT * FROM items ORDER BY a, b
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# File 'lib/sequel/dataset/query.rb', line 620 def order_more(*columns, &block) columns = @opts[:order] + columns if @opts[:order] order(*columns, &block) end |
#order_prepend(*columns, &block) ⇒ Object
Returns a copy of the dataset with the order columns added to the beginning of the existing order.
DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
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# File 'lib/sequel/dataset/query.rb', line 630 def order_prepend(*columns, &block) ds = order(*columns, &block) @opts[:order] ? ds.order_more(*@opts[:order]) : ds end |
#ordered_expression_sql_append(sql, oe) ⇒ Object
SQL fragment for the ordered expression, used in the ORDER BY clause.
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# File 'lib/sequel/dataset/sql.rb', line 520 def ordered_expression_sql_append(sql, oe) literal_append(sql, oe.expression) sql << (oe.descending ? DESC : ASC) case oe.nulls when :first sql << NULLS_FIRST when :last sql << NULLS_LAST end end |
#paged_each(opts = OPTS) ⇒ Object
Yields each row in the dataset, but interally uses multiple queries as needed with limit and offset to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.
Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to make sure that all rows in the dataset are yielded and none are yielded twice, the dataset must have an unambiguous order. Sequel requires that datasets using this method have an order, but it cannot ensure that the order is unambiguous.
Options:
- :rows_per_fetch
-
The number of rows to fetch per query. Defaults to 1000.
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# File 'lib/sequel/dataset/actions.rb', line 448 def paged_each(opts=OPTS) unless @opts[:order] raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered" end total_limit = @opts[:limit] offset = @opts[:offset] || 0 if server = @opts[:server] opts = opts.merge(:server=>server) end rows_per_fetch = opts[:rows_per_fetch] || 1000 num_rows_yielded = rows_per_fetch total_rows = 0 db.transaction(opts) do while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit) if total_limit && total_rows + rows_per_fetch > total_limit rows_per_fetch = total_limit - total_rows end num_rows_yielded = 0 limit(rows_per_fetch, offset).each do |row| num_rows_yielded += 1 total_rows += 1 if total_limit yield row end offset += rows_per_fetch end end self end |
#placeholder_literal_string_sql_append(sql, pls) ⇒ Object
SQL fragment for a literal string with placeholders
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# File 'lib/sequel/dataset/sql.rb', line 532 def placeholder_literal_string_sql_append(sql, pls) args = pls.args str = pls.str sql << PAREN_OPEN if pls.parens if args.is_a?(Hash) if args.empty? sql << str else re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/ loop do previous, q, str = str.partition(re) sql << previous literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty? break if str.empty? end end elsif str.is_a?(Array) len = args.length str.each_with_index do |s, i| sql << s literal_append(sql, args[i]) unless i == len end unless str.length == args.length || str.length == args.length + 1 raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array" end else i = -1 match_len = args.length - 1 loop do previous, q, str = str.partition(QUESTION_MARK) sql << previous literal_append(sql, args.at(i+=1)) unless q.empty? if str.empty? unless i == match_len raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder array" end break end end end sql << PAREN_CLOSE if pls.parens end |
#prepare(type, name = nil, *values) ⇒ Object
Prepare an SQL statement for later execution. Takes a type similar to #call, and the name
symbol of the prepared statement. While name
defaults to nil
, it should always be provided as a symbol for the name of the prepared statement, as some databases require that prepared statements have names.
This returns a clone of the dataset extended with PreparedStatementMethods, which you can call
with the hash of bind variables to use. The prepared statement is also stored in the associated database, where it can be called by name. The following usage is identical:
ps = DB[:table].filter(:name=>:$name).prepare(:first, :select_by_name)
ps.call(:name=>'Blah')
# SELECT * FROM table WHERE name = ? -- ('Blah')
# => {:id=>1, :name=>'Blah'}
DB.call(:select_by_name, :name=>'Blah') # Same thing
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# File 'lib/sequel/dataset/prepared_statements.rb', line 250 def prepare(type, name=nil, *values) ps = to_prepared_statement(type, values) db.set_prepared_statement(name, ps) if name ps end |
#provides_accurate_rows_matched? ⇒ Boolean
Whether this dataset will provide accurate number of rows matched for delete and update statements. Accurate in this case is the number of rows matched by the dataset’s filter.
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# File 'lib/sequel/dataset/features.rb', line 21 def provides_accurate_rows_matched? true end |
#qualified_identifier_sql_append(sql, table, column = (c = table.column; table = table.table; c)) ⇒ Object
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table). If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.
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# File 'lib/sequel/dataset/sql.rb', line 579 def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) identifier_append(sql, table) sql << DOT identifier_append(sql, column) end |
#qualify(table = first_source) ⇒ Object
Qualify to the given table, or first source if no table is given.
DB[:items].where(:id=>1).qualify
# SELECT items.* FROM items WHERE (items.id = 1)
DB[:items].where(:id=>1).qualify(:i)
# SELECT i.* FROM items WHERE (i.id = 1)
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# File 'lib/sequel/dataset/query.rb', line 642 def qualify(table=first_source) o = @opts return clone if o[:sql] h = {} (o.keys & QUALIFY_KEYS).each do |k| h[k] = qualified_expression(o[k], table) end h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty? clone(h) end |
#quote_identifier_append(sql, name) ⇒ Object
Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.
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# File 'lib/sequel/dataset/sql.rb', line 588 def quote_identifier_append(sql, name) if name.is_a?(LiteralString) sql << name else name = name.value if name.is_a?(SQL::Identifier) name = input_identifier(name) if quote_identifiers? quoted_identifier_append(sql, name) else sql << name end end end |
#quote_identifiers=(v) ⇒ Object
Set whether to quote identifiers for this dataset
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# File 'lib/sequel/dataset/mutation.rb', line 78 def quote_identifiers=(v) raise_if_frozen! @quote_identifiers = v end |
#quote_identifiers? ⇒ Boolean
Whether this dataset quotes identifiers.
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# File 'lib/sequel/dataset/features.rb', line 10 def quote_identifiers? if defined?(@quote_identifiers) @quote_identifiers else @quote_identifiers = db.quote_identifiers? end end |
#quote_schema_table_append(sql, table) ⇒ Object
Separates the schema from the table and returns a string with them quoted (if quoting identifiers)
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# File 'lib/sequel/dataset/sql.rb', line 604 def quote_schema_table_append(sql, table) schema, table = schema_and_table(table) if schema quote_identifier_append(sql, schema) sql << DOT end quote_identifier_append(sql, table) end |
#quoted_identifier_append(sql, name) ⇒ Object
This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).
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# File 'lib/sequel/dataset/sql.rb', line 616 def quoted_identifier_append(sql, name) sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE end |
#range(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns a Range
instance made from the minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1
# => 1..10
DB[:table].interval{function(column)} # SELECT max(function(column)) AS v1, min(function(column)) AS v2 FROM table LIMIT 1
# => 0..7
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# File 'lib/sequel/dataset/actions.rb', line 491 def range(column=Sequel.virtual_row(&Proc.new)) if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first (r[:v1]..r[:v2]) end end |
#recursive_cte_requires_column_aliases? ⇒ Boolean
Whether you must use a column alias list for recursive CTEs (false by default).
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# File 'lib/sequel/dataset/features.rb', line 27 def recursive_cte_requires_column_aliases? false end |
#requires_placeholder_type_specifiers? ⇒ Boolean
Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer)
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# File 'lib/sequel/dataset/features.rb', line 39 def requires_placeholder_type_specifiers? false end |
#requires_sql_standard_datetimes? ⇒ Boolean
Whether the dataset requires SQL standard datetimes (false by default, as most allow strings with ISO 8601 format).
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# File 'lib/sequel/dataset/features.rb', line 33 def requires_sql_standard_datetimes? false end |
#returning(*values) ⇒ Object
Modify the RETURNING clause, only supported on a few databases. If returning is used, instead of insert returning the autogenerated primary key or update/delete returning the number of modified rows, results are returned using fetch_rows
.
DB[:items].returning # RETURNING *
DB[:items].returning(nil) # RETURNING NULL
DB[:items].returning(:id, :name) # RETURNING id, name
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# File 'lib/sequel/dataset/query.rb', line 661 def returning(*values) clone(:returning=>values) end |
#reverse(*order, &block) ⇒ Object
Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.
DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC
DB[:items].reverse{foo()} # SELECT * FROM items ORDER BY foo(bar) DESC
DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
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# File 'lib/sequel/dataset/query.rb', line 672 def reverse(*order, &block) virtual_row_columns(order, block) order(*invert_order(order.empty? ? @opts[:order] : order)) end |
#reverse_order(*order, &block) ⇒ Object
Alias of reverse
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# File 'lib/sequel/dataset/query.rb', line 678 def reverse_order(*order, &block) reverse(*order, &block) end |
#row_number_column ⇒ Object
The alias to use for the row_number column, used when emulating OFFSET support and for eager limit strategies
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# File 'lib/sequel/dataset/misc.rb', line 168 def row_number_column :x_sequel_row_number_x end |
#schema_and_table(table_name, sch = nil) ⇒ Object
Split the schema information from the table, returning two strings, one for the schema and one for the table. The returned schema may be nil, but the table will always have a string value.
Note that this function does not handle tables with more than one level of qualification (e.g. database.schema.table on Microsoft SQL Server).
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# File 'lib/sequel/dataset/sql.rb', line 627 def schema_and_table(table_name, sch=nil) sch = sch.to_s if sch case table_name when Symbol s, t, _ = split_symbol(table_name) [s||sch, t] when SQL::QualifiedIdentifier [table_name.table.to_s, table_name.column.to_s] when SQL::Identifier [sch, table_name.value.to_s] when String [sch, table_name] else raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String' end end |
#select(*columns, &block) ⇒ Object
Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to where
.
DB[:items].select(:a) # SELECT a FROM items
DB[:items].select(:a, :b) # SELECT a, b FROM items
DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
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# File 'lib/sequel/dataset/query.rb', line 689 def select(*columns, &block) virtual_row_columns(columns, block) clone(:select => columns) end |
#select_all(*tables) ⇒ Object
Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.
DB[:items].select(:a).select_all # SELECT * FROM items
DB[:items].select_all(:items) # SELECT items.* FROM items
DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
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# File 'lib/sequel/dataset/query.rb', line 701 def select_all(*tables) if tables.empty? clone(:select => nil) else select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)}) end end |
#select_append(*columns, &block) ⇒ Object
Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.
DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items
DB[:items].select_append(:b) # SELECT *, b FROM items
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# File 'lib/sequel/dataset/query.rb', line 716 def select_append(*columns, &block) cur_sel = @opts[:select] if !cur_sel || cur_sel.empty? unless supports_select_all_and_column? return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block) end cur_sel = [WILDCARD] end select(*(cur_sel + columns), &block) end |
#select_group(*columns, &block) ⇒ Object
Set both the select and group clauses with the given columns
. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to where
.
DB[:items].select_group(:a, :b)
# SELECT a, b FROM items GROUP BY a, b
DB[:items].select_group(:c___a){f(c2)}
# SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
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# File 'lib/sequel/dataset/query.rb', line 736 def select_group(*columns, &block) virtual_row_columns(columns, block) select(*columns).group(*columns.map{|c| unaliased_identifier(c)}) end |
#select_hash(key_column, value_column) ⇒ Object
Returns a hash with key_column values as keys and value_column values as values. Similar to to_hash, but only selects the columns given.
DB[:table].select_hash(:id, :name) # SELECT id, name FROM table
# => {1=>'a', 2=>'b', ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].select_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['a', 'c'], [2, 4]=>['b', 'd'], ...}
When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the #as method on the expression and providing an alias.
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# File 'lib/sequel/dataset/actions.rb', line 512 def select_hash(key_column, value_column) _select_hash(:to_hash, key_column, value_column) end |
#select_hash_groups(key_column, value_column) ⇒ Object
Returns a hash with key_column values as keys and an array of value_column values. Similar to to_hash_groups, but only selects the columns given.
DB[:table].select_hash(:name, :id) # SELECT id, name FROM table
# => {'a'=>[1, 4, ...], 'b'=>[2, ...], ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].select_hash([:first, :middle], [:last, :id]) # SELECT * FROM table
# {['a', 'b']=>[['c', 1], ['d', 2], ...], ...}
When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the #as method on the expression and providing an alias.
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# File 'lib/sequel/dataset/actions.rb', line 531 def select_hash_groups(key_column, value_column) _select_hash(:to_hash_groups, key_column, value_column) end |
#select_map(column = nil, &block) ⇒ Object
Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset. If you give a block argument that returns an array with multiple entries, the contents of the resulting array are undefined. Raises an Error if called with both an argument and a block.
DB[:table].select_map(:id) # SELECT id FROM table
# => [3, 5, 8, 1, ...]
DB[:table].select_map{id * 2} # SELECT (id * 2) FROM table
# => [6, 10, 16, 2, ...]
You can also provide an array of column names:
DB[:table].select_map([:id, :name]) # SELECT id, name FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the #as method on the expression and providing an alias.
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# File 'lib/sequel/dataset/actions.rb', line 555 def select_map(column=nil, &block) _select_map(column, false, &block) end |
#select_more(*columns, &block) ⇒ Object
Alias for select_append.
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# File 'lib/sequel/dataset/query.rb', line 742 def select_more(*columns, &block) select_append(*columns, &block) end |
#select_order_map(column = nil, &block) ⇒ Object
The same as select_map, but in addition orders the array by the column.
DB[:table].select_order_map(:id) # SELECT id FROM table ORDER BY id
# => [1, 2, 3, 4, ...]
DB[:table].select_order_map{id * 2} # SELECT (id * 2) FROM table ORDER BY (id * 2)
# => [2, 4, 6, 8, ...]
You can also provide an array of column names:
DB[:table].select_order_map([:id, :name]) # SELECT id, name FROM table ORDER BY id, name
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the #as method on the expression and providing an alias.
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# File 'lib/sequel/dataset/actions.rb', line 575 def select_order_map(column=nil, &block) _select_map(column, true, &block) end |
#select_sql ⇒ Object
Returns a SELECT SQL query string.
dataset.select_sql # => "SELECT * FROM items"
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# File 'lib/sequel/dataset/sql.rb', line 132 def select_sql return static_sql(@opts[:sql]) if @opts[:sql] clause_sql(:select) end |
#server(servr) ⇒ Object
Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.
DB[:items].all # Uses the :read_only or :default server
DB[:items].delete # Uses the :default server
DB[:items].server(:blah).delete # Uses the :blah server
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# File 'lib/sequel/dataset/query.rb', line 755 def server(servr) clone(:server=>servr) end |
#set_graph_aliases(graph_aliases) ⇒ Object
This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of select
for a graphed dataset, and must be used instead of select
whenever graphing is used.
- graph_aliases
-
Should be a hash with keys being symbols of column aliases, and values being either symbols or arrays with one to three elements. If the value is a symbol, it is assumed to be the same as a one element array containing that symbol. The first element of the array should be the table alias symbol. The second should be the actual column name symbol. If the array only has a single element the column name symbol will be assumed to be the same as the corresponding hash key. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.
DB[:artists].graph(:albums, :artist_id=>:id).
set_graph_aliases(:name=>:artists,
:album_name=>[:albums, :name],
:forty_two=>[:albums, :fourtwo, 42]).first
# SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
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# File 'lib/sequel/dataset/graph.rb', line 203 def set_graph_aliases(graph_aliases) columns, graph_aliases = graph_alias_columns(graph_aliases) ds = select(*columns) ds.opts[:graph_aliases] = graph_aliases ds end |
#single_record ⇒ Object
Returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first
instead of this method.
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# File 'lib/sequel/dataset/actions.rb', line 582 def single_record clone(:limit=>1).each{|r| return r} nil end |
#single_value ⇒ Object
Returns the first value of the first record in the dataset. Returns nil if dataset is empty. Users should generally use get
instead of this method.
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# File 'lib/sequel/dataset/actions.rb', line 590 def single_value if r = ungraphed.naked.single_record r.values.first end end |
#split_alias(c) ⇒ Object
Splits a possible implicit alias in c
, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.
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# File 'lib/sequel/dataset/misc.rb', line 175 def split_alias(c) case c when Symbol c_table, column, aliaz = split_symbol(c) [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz] when SQL::AliasedExpression [c.expression, c.aliaz] when SQL::JoinClause [c.table, c.table_alias] else [c, nil] end end |
#split_qualifiers(table_name, *args) ⇒ Object
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# File 'lib/sequel/dataset/sql.rb', line 650 def split_qualifiers(table_name, *args) case table_name when SQL::QualifiedIdentifier split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil) else sch, table = schema_and_table(table_name, *args) sch ? [sch, table] : [table] end end |
#sql ⇒ Object
Same as select_sql
, not aliased directly to make subclassing simpler.
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# File 'lib/sequel/dataset/sql.rb', line 138 def sql select_sql end |
#subscript_sql_append(sql, s) ⇒ Object
SQL fragment for specifying subscripts (SQL array accesses)
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# File 'lib/sequel/dataset/sql.rb', line 661 def subscript_sql_append(sql, s) literal_append(sql, s.f) sql << BRACKET_OPEN if s.sub.length == 1 && (range = s.sub.first).is_a?(Range) literal_append(sql, range.begin) sql << COLON e = range.end e -= 1 if range.exclude_end? && e.is_a?(Integer) literal_append(sql, e) else expression_list_append(sql, s.sub) end sql << BRACKET_CLOSE end |
#sum(column = Sequel.virtual_row(&Proc.new)) ⇒ Object
Returns the sum for the given column/expression. Uses a virtual row block if no column is given.
DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
# => 55
DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1
# => 10
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# File 'lib/sequel/dataset/actions.rb', line 603 def sum(column=Sequel.virtual_row(&Proc.new)) aggregate_dataset.get{sum(column).as(:sum)} end |
#supports_cte?(type = :select) ⇒ Boolean
Whether the dataset supports common table expressions (the WITH clause). If given, type
can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.
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# File 'lib/sequel/dataset/features.rb', line 46 def supports_cte?(type=:select) send(:"#{type}_clause_methods").include?(:"#{type}_with_sql") end |
#supports_cte_in_subqueries? ⇒ Boolean
Whether the dataset supports common table expressions (the WITH clause) in subqueries. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.
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# File 'lib/sequel/dataset/features.rb', line 53 def supports_cte_in_subqueries? false end |
#supports_distinct_on? ⇒ Boolean
Whether the dataset supports or can emulate the DISTINCT ON clause, false by default.
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# File 'lib/sequel/dataset/features.rb', line 58 def supports_distinct_on? false end |
#supports_group_cube? ⇒ Boolean
Whether the dataset supports CUBE with GROUP BY.
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# File 'lib/sequel/dataset/features.rb', line 63 def supports_group_cube? false end |
#supports_group_rollup? ⇒ Boolean
Whether the dataset supports ROLLUP with GROUP BY.
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# File 'lib/sequel/dataset/features.rb', line 68 def supports_group_rollup? false end |
#supports_insert_select? ⇒ Boolean
Whether this dataset supports the insert_select
method for returning all columns values directly from an insert query.
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# File 'lib/sequel/dataset/features.rb', line 74 def supports_insert_select? supports_returning?(:insert) end |
#supports_intersect_except? ⇒ Boolean
Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.
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# File 'lib/sequel/dataset/features.rb', line 79 def supports_intersect_except? true end |
#supports_intersect_except_all? ⇒ Boolean
Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.
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# File 'lib/sequel/dataset/features.rb', line 84 def supports_intersect_except_all? true end |
#supports_is_true? ⇒ Boolean
Whether the dataset supports the IS TRUE syntax.
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# File 'lib/sequel/dataset/features.rb', line 89 def supports_is_true? true end |
#supports_join_using? ⇒ Boolean
Whether the dataset supports the JOIN table USING (column1, …) syntax.
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# File 'lib/sequel/dataset/features.rb', line 94 def supports_join_using? true end |
#supports_lateral_subqueries? ⇒ Boolean
Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses.
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# File 'lib/sequel/dataset/features.rb', line 99 def supports_lateral_subqueries? false end |
#supports_modifying_joins? ⇒ Boolean
Whether modifying joined datasets is supported.
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# File 'lib/sequel/dataset/features.rb', line 104 def false end |
#supports_multiple_column_in? ⇒ Boolean
Whether the IN/NOT IN operators support multiple columns when an array of values is given.
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# File 'lib/sequel/dataset/features.rb', line 110 def supports_multiple_column_in? true end |
#supports_ordered_distinct_on? ⇒ Boolean
Whether the dataset supports or can fully emulate the DISTINCT ON clause, including respecting the ORDER BY clause, false by default
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# File 'lib/sequel/dataset/features.rb', line 116 def supports_ordered_distinct_on? supports_distinct_on? end |
#supports_regexp? ⇒ Boolean
Whether the dataset supports pattern matching by regular expressions.
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# File 'lib/sequel/dataset/features.rb', line 121 def supports_regexp? false end |
#supports_replace? ⇒ Boolean
Whether the dataset supports REPLACE syntax, false by default.
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# File 'lib/sequel/dataset/features.rb', line 126 def supports_replace? false end |
#supports_returning?(type) ⇒ Boolean
Whether the RETURNING clause is supported for the given type of query. type
can be :insert, :update, or :delete.
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# File 'lib/sequel/dataset/features.rb', line 132 def supports_returning?(type) send(:"#{type}_clause_methods").include?(:"#{type}_returning_sql") end |
#supports_select_all_and_column? ⇒ Boolean
Whether the database supports SELECT *, column FROM table
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# File 'lib/sequel/dataset/features.rb', line 137 def supports_select_all_and_column? true end |
#supports_timestamp_timezones? ⇒ Boolean
Whether the dataset supports timezones in literal timestamps
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# File 'lib/sequel/dataset/features.rb', line 142 def false end |
#supports_timestamp_usecs? ⇒ Boolean
Whether the dataset supports fractional seconds in literal timestamps
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# File 'lib/sequel/dataset/features.rb', line 147 def true end |
#supports_where_true? ⇒ Boolean
Whether the dataset supports WHERE TRUE (or WHERE 1 for databases that that use 1 for true).
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# File 'lib/sequel/dataset/features.rb', line 158 def supports_where_true? true end |
#supports_window_functions? ⇒ Boolean
Whether the dataset supports window functions.
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# File 'lib/sequel/dataset/features.rb', line 152 def supports_window_functions? false end |
#to_hash(key_column, value_column = nil) ⇒ Object
Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.
DB[:table].to_hash(:id, :name) # SELECT * FROM table
# {1=>'Jim', 2=>'Bob', ...}
DB[:table].to_hash(:id) # SELECT * FROM table
# {1=>{:id=>1, :name=>'Jim'}, 2=>{:id=>2, :name=>'Bob'}, ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].to_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...}
DB[:table].to_hash([:id, :name]) # SELECT * FROM table
# {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob'=>{:id=>2, :name=>'Bob'}, ...}
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# File 'lib/sequel/dataset/actions.rb', line 626 def to_hash(key_column, value_column = nil) h = {} if value_column return naked.to_hash(key_column, value_column) if row_proc if value_column.is_a?(Array) if key_column.is_a?(Array) each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)} else each{|r| h[r[key_column]] = r.values_at(*value_column)} end else if key_column.is_a?(Array) each{|r| h[r.values_at(*key_column)] = r[value_column]} else each{|r| h[r[key_column]] = r[value_column]} end end elsif key_column.is_a?(Array) each{|r| h[r.values_at(*key_column)] = r} else each{|r| h[r[key_column]] = r} end h end |
#to_hash_groups(key_column, value_column = nil) ⇒ Object
Returns a hash with one column used as key and the values being an array of column values. If the value_column is not given or nil, uses the entire hash as the value.
DB[:table].to_hash(:name, :id) # SELECT * FROM table
# {'Jim'=>[1, 4, 16, ...], 'Bob'=>[2], ...}
DB[:table].to_hash(:name) # SELECT * FROM table
# {'Jim'=>[{:id=>1, :name=>'Jim'}, {:id=>4, :name=>'Jim'}, ...], 'Bob'=>[{:id=>2, :name=>'Bob'}], ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].to_hash([:first, :middle], [:last, :id]) # SELECT * FROM table
# {['Jim', 'Bob']=>[['Smith', 1], ['Jackson', 4], ...], ...}
DB[:table].to_hash([:first, :middle]) # SELECT * FROM table
# {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}
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# File 'lib/sequel/dataset/actions.rb', line 669 def to_hash_groups(key_column, value_column = nil) h = {} if value_column return naked.to_hash_groups(key_column, value_column) if row_proc if value_column.is_a?(Array) if key_column.is_a?(Array) each{|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)} else each{|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)} end else if key_column.is_a?(Array) each{|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]} else each{|r| (h[r[key_column]] ||= []) << r[value_column]} end end elsif key_column.is_a?(Array) each{|r| (h[r.values_at(*key_column)] ||= []) << r} else each{|r| (h[r[key_column]] ||= []) << r} end h end |
#truncate ⇒ Object
Truncates the dataset. Returns nil.
DB[:table].truncate # TRUNCATE table
# => nil
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# File 'lib/sequel/dataset/actions.rb', line 698 def truncate execute_ddl(truncate_sql) end |
#truncate_sql ⇒ Object
Returns a TRUNCATE SQL query string. See truncate
DB[:items].truncate_sql # => 'TRUNCATE items'
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# File 'lib/sequel/dataset/sql.rb', line 145 def truncate_sql if opts[:sql] static_sql(opts[:sql]) else check_truncation_allowed! raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having] t = '' source_list_append(t, opts[:from]) _truncate_sql(t) end end |
#unbind ⇒ Object
Unbind bound variables from this dataset’s filter and return an array of two objects. The first object is a modified dataset where the filter has been replaced with one that uses bound variable placeholders. The second object is the hash of unbound variables. You can then prepare and execute (or just call) the dataset with the bound variables to get results.
ds, bv = DB[:items].where(:a=>1).unbind
ds # SELECT * FROM items WHERE (a = $a)
bv # {:a => 1}
ds.call(:select, bv)
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# File 'lib/sequel/dataset/query.rb', line 769 def unbind u = Unbinder.new ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join])) [ds, u.binds] end |
#unfiltered ⇒ Object
Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.
DB[:items].group(:a).having(:a=>1).where(:b).unfiltered
# SELECT * FROM items GROUP BY a
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# File 'lib/sequel/dataset/query.rb', line 779 def unfiltered clone(:where => nil, :having => nil) end |
#ungraphed ⇒ Object
Remove the splitting of results into subhashes, and all metadata related to the current graph (if any).
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# File 'lib/sequel/dataset/graph.rb', line 212 def ungraphed clone(:graph=>nil, :graph_aliases=>nil) end |
#ungrouped ⇒ Object
Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.
DB[:items].group(:a).having(:a=>1).where(:b).ungrouped
# SELECT * FROM items WHERE b
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# File 'lib/sequel/dataset/query.rb', line 787 def ungrouped clone(:group => nil, :having => nil) end |
#union(dataset, opts = OPTS) ⇒ Object
Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:
- :alias
-
Use the given value as the from_self alias
- :all
-
Set to true to use UNION ALL instead of UNION, so duplicate rows can occur
- :from_self
-
Set to false to not wrap the returned dataset in a from_self, use with care.
DB[:items].union(DB[:other_items])
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1
DB[:items].union(DB[:other_items], :all=>true, :from_self=>false)
# SELECT * FROM items UNION ALL SELECT * FROM other_items
DB[:items].union(DB[:other_items], :alias=>:i)
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
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# File 'lib/sequel/dataset/query.rb', line 807 def union(dataset, opts=OPTS) compound_clone(:union, dataset, opts) end |
#unlimited ⇒ Object
Returns a copy of the dataset with no limit or offset.
DB[:items].limit(10, 20).unlimited # SELECT * FROM items
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# File 'lib/sequel/dataset/query.rb', line 814 def unlimited clone(:limit=>nil, :offset=>nil) end |
#unordered ⇒ Object
Returns a copy of the dataset with no order.
DB[:items].order(:a).unordered # SELECT * FROM items
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# File 'lib/sequel/dataset/query.rb', line 821 def unordered order(nil) end |
#unused_table_alias(table_alias, used_aliases = []) ⇒ Object
Creates a unique table alias that hasn’t already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with “_N” if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.
You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.
DB[:table].unused_table_alias(:t)
# => :t
DB[:table].unused_table_alias(:table)
# => :table_0
DB[:table, :table_0].unused_table_alias(:table)
# => :table_1
DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2])
# => :table_3
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# File 'lib/sequel/dataset/misc.rb', line 211 def unused_table_alias(table_alias, used_aliases = []) table_alias = alias_symbol(table_alias) used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from] used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join] if used_aliases.include?(table_alias) i = 0 loop do ta = :"#{table_alias}_#{i}" return ta unless used_aliases.include?(ta) i += 1 end else table_alias end end |
#update(values = OPTS, &block) ⇒ Object
Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent. values
should a hash where the keys are columns to set and values are the values to which to set the columns.
DB[:table].update(:x=>nil) # UPDATE table SET x = NULL
# => 10
DB[:table].update(:x=>:x+1, :y=>0) # UPDATE table SET x = (x + 1), y = 0
# => 10
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# File 'lib/sequel/dataset/actions.rb', line 712 def update(values=OPTS, &block) sql = update_sql(values) if uses_returning?(:update) returning_fetch_rows(sql, &block) else execute_dui(sql) end end |
#update_sql(values = OPTS) ⇒ Object
Formats an UPDATE statement using the given values. See update
.
DB[:items].update_sql(:price => 100, :category => 'software')
# => "UPDATE items SET price = 100, category = 'software'
Raises an Error
if the dataset is grouped or includes more than one table.
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# File 'lib/sequel/dataset/sql.rb', line 164 def update_sql(values = OPTS) return static_sql(opts[:sql]) if opts[:sql] check_modification_allowed! clone(:values=>values)._update_sql end |
#where(*cond, &block) ⇒ Object
Returns a copy of the dataset with the given WHERE conditions imposed upon it.
Accepts the following argument types:
-
Hash - list of equality/inclusion expressions
-
Array - depends:
-
If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.
-
If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.
-
Otherwise, treats each argument as a separate condition.
-
-
String - taken literally
-
Symbol - taken as a boolean column argument (e.g. WHERE active)
-
Sequel::SQL::BooleanExpression - an existing condition expression, probably created using the Sequel expression filter DSL.
where also accepts a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions. For more details on the virtual row support, see the “Virtual Rows” guide
If both a block and regular argument are provided, they get ANDed together.
Examples:
DB[:items].where(:id => 3)
# SELECT * FROM items WHERE (id = 3)
DB[:items].where('price < ?', 100)
# SELECT * FROM items WHERE price < 100
DB[:items].where([[:id, [1,2,3]], [:id, 0..10]])
# SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))
DB[:items].where('price < 100')
# SELECT * FROM items WHERE price < 100
DB[:items].where(:active)
# SELECT * FROM items WHERE :active
DB[:items].where{price < 100}
# SELECT * FROM items WHERE (price < 100)
Multiple where calls can be chained for scoping:
software = dataset.where(:category => 'software').where{price < 100}
# SELECT * FROM items WHERE ((category = 'software') AND (price < 100))
See the the “Dataset Filtering” guide for more examples and details.
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# File 'lib/sequel/dataset/query.rb', line 875 def where(*cond, &block) _filter(:where, *cond, &block) end |
#window_function_sql_append(sql, function, window) ⇒ Object
The SQL fragment for the given window function’s function and window.
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# File 'lib/sequel/dataset/sql.rb', line 718 def window_function_sql_append(sql, function, window) literal_append(sql, function) sql << OVER literal_append(sql, window) end |
#window_sql_append(sql, opts) ⇒ Object
The SQL fragment for the given window’s options.
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# File 'lib/sequel/dataset/sql.rb', line 677 def window_sql_append(sql, opts) raise(Error, 'This dataset does not support window functions') unless supports_window_functions? sql << PAREN_OPEN window, part, order, frame = opts.values_at(:window, :partition, :order, :frame) space = false space_s = SPACE if window literal_append(sql, window) space = true end if part sql << space_s if space sql << PARTITION_BY expression_list_append(sql, Array(part)) space = true end if order sql << space_s if space sql << ORDER_BY_NS expression_list_append(sql, Array(order)) space = true end case frame when nil # nothing when :all sql << space_s if space sql << FRAME_ALL when :rows sql << space_s if space sql << FRAME_ROWS when String sql << space_s if space sql << frame else raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil" end sql << PAREN_CLOSE end |
#with(name, dataset, opts = OPTS) ⇒ Object
Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query. Options:
- :args
-
Specify the arguments/columns for the CTE, should be an array of symbols.
- :recursive
-
Specify that this is a recursive CTE
DB[:items].with(:items, DB[:syx].where(:name.like('A%')))
# WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%')) SELECT * FROM items
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# File 'lib/sequel/dataset/query.rb', line 887 def with(name, dataset, opts=OPTS) raise(Error, 'This datatset does not support common table expressions') unless supports_cte? if hoist_cte?(dataset) s, ds = hoist_cte(dataset) s.with(name, ds, opts) else clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)]) end end |
#with_recursive(name, nonrecursive, recursive, opts = OPTS) ⇒ Object
Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE. Options:
- :args
-
Specify the arguments/columns for the CTE, should be an array of symbols.
- :union_all
-
Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts.
DB[:t].with_recursive(:t,
DB[:i1].select(:id, :parent_id).where(:parent_id=>nil),
DB[:i1].join(:t, :id=>:parent_id).select(:i1__id, :i1__parent_id),
:args=>[:id, :parent_id])
# WITH RECURSIVE "t"("id", "parent_id") AS (
# SELECT "id", "parent_id" FROM "i1" WHERE ("parent_id" IS NULL)
# UNION ALL
# SELECT "i1"."id", "i1"."parent_id" FROM "i1" INNER JOIN "t" ON ("t"."id" = "i1"."parent_id")
# ) SELECT * FROM "t"
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# File 'lib/sequel/dataset/query.rb', line 913 def with_recursive(name, nonrecursive, recursive, opts=OPTS) raise(Error, 'This datatset does not support common table expressions') unless supports_cte? if hoist_cte?(nonrecursive) s, ds = hoist_cte(nonrecursive) s.with_recursive(name, ds, recursive, opts) elsif hoist_cte?(recursive) s, ds = hoist_cte(recursive) s.with_recursive(name, nonrecursive, ds, opts) else clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]) end end |
#with_sql(sql, *args) ⇒ Object
Returns a copy of the dataset with the static SQL used. This is useful if you want to keep the same row_proc/graph, but change the SQL used to custom SQL.
DB[:items].with_sql('SELECT * FROM foo') # SELECT * FROM foo
You can use placeholders in your SQL and provide arguments for those placeholders:
DB[:items].with_sql('SELECT ? FROM foo', 1) # SELECT 1 FROM foo
You can also provide a method name and arguments to call to get the SQL:
DB[:items].with_sql(:insert_sql, :b=>1) # INSERT INTO items (b) VALUES (1)
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# File 'lib/sequel/dataset/query.rb', line 938 def with_sql(sql, *args) if sql.is_a?(Symbol) sql = send(sql, *args) else sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty? end clone(:sql=>sql) end |
#with_sql_delete(sql) ⇒ Object
Execute the given SQL and return the number of rows deleted. This exists solely as an optimization, replacing with_sql(sql).delete. It’s significantly faster as it does not require cloning the current dataset.
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# File 'lib/sequel/dataset/actions.rb', line 724 def with_sql_delete(sql) execute_dui(sql) end |