Class: SQLite3::Database

Inherits:
Object
  • Object
show all
Includes:
Pragmas
Defined in:
lib/sqlite3/database.rb,
ext/sqlite3/database.c

Overview

The Database class encapsulates a single connection to a SQLite3 database. Its usage is very straightforward:

require 'sqlite3'

SQLite3::Database.new( "data.db" ) do |db|
  db.execute( "select * from table" ) do |row|
    p row
  end
end

It wraps the lower-level methods provided by the selected driver, and includes the Pragmas module for access to various pragma convenience methods.

The Database class provides type translation services as well, by which the SQLite3 data types (which are all represented as strings) may be converted into their corresponding types (as defined in the schemas for their tables). This translation only occurs when querying data from the database–insertions and updates are all still typeless.

Furthermore, the Database class has been designed to work well with the ArrayFields module from Ara Howard. If you require the ArrayFields module before performing a query, and if you have not enabled results as hashes, then the results will all be indexible by field name.

Thread safety:

When ‘SQLite3.threadsafe?` returns true, it is safe to share instances of the database class among threads without adding specific locking. Other object instances may require applications to provide their own locks if they are to be shared among threads. Please see the README.md for more information.

Defined Under Namespace

Classes: FunctionProxy

Constant Summary

Constants included from Pragmas

Pragmas::AUTO_VACUUM_MODES, Pragmas::ENCODINGS, Pragmas::JOURNAL_MODES, Pragmas::LOCKING_MODES, Pragmas::SYNCHRONOUS_MODES, Pragmas::TEMP_STORE_MODES, Pragmas::WAL_CHECKPOINTS

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Pragmas

#application_id, #application_id=, #auto_vacuum, #auto_vacuum=, #automatic_index, #automatic_index=, #cache_size, #cache_size=, #cache_spill, #cache_spill=, #case_sensitive_like=, #cell_size_check, #cell_size_check=, #checkpoint_fullfsync, #checkpoint_fullfsync=, #collation_list, #compile_options, #count_changes, #count_changes=, #data_version, #database_list, #default_cache_size, #default_cache_size=, #default_synchronous, #default_synchronous=, #default_temp_store, #default_temp_store=, #defer_foreign_keys, #defer_foreign_keys=, #encoding=, #foreign_key_check, #foreign_key_list, #foreign_keys, #foreign_keys=, #freelist_count, #full_column_names, #full_column_names=, #fullfsync, #fullfsync=, #get_boolean_pragma, #get_enum_pragma, #get_int_pragma, #get_query_pragma, #ignore_check_constraints=, #incremental_vacuum, #index_info, #index_list, #index_xinfo, #integrity_check, #journal_mode, #journal_mode=, #journal_size_limit, #journal_size_limit=, #legacy_file_format, #legacy_file_format=, #locking_mode, #locking_mode=, #max_page_count, #max_page_count=, #mmap_size, #mmap_size=, #optimize, #page_count, #page_size, #page_size=, #parser_trace=, #query_only, #query_only=, #quick_check, #read_uncommitted, #read_uncommitted=, #recursive_triggers, #recursive_triggers=, #reverse_unordered_selects, #reverse_unordered_selects=, #schema_cookie, #schema_cookie=, #schema_version, #schema_version=, #secure_delete, #secure_delete=, #set_boolean_pragma, #set_enum_pragma, #set_int_pragma, #short_column_names, #short_column_names=, #shrink_memory, #soft_heap_limit, #soft_heap_limit=, #stats, #synchronous, #synchronous=, #table_info, #temp_store, #temp_store=, #threads, #threads=, #user_cookie, #user_cookie=, #user_version, #user_version=, #vdbe_addoptrace=, #vdbe_debug=, #vdbe_listing=, #vdbe_trace, #vdbe_trace=, #wal_autocheckpoint, #wal_autocheckpoint=, #wal_checkpoint, #wal_checkpoint=, #writable_schema=

Constructor Details

#initialize(file, options = {}, zvfs = nil) ⇒ Database

call-seq: SQLite3::Database.new(file, options = {})

Create a new Database object that opens the given file.

Supported permissions options:

  • the default mode is READWRITE | CREATE

  • :readonly: boolean (default false), true to set the mode to READONLY

  • :readwrite: boolean (default false), true to set the mode to READWRITE

  • :flags: set the mode to a combination of SQLite3::Constants::Open flags.

Supported encoding options:

  • :utf16: boolean (default false), is the filename’s encoding UTF-16 (only needed if the filename encoding is not UTF_16LE or BE)

Other supported options:

  • :strict: boolean (default false), disallow the use of double-quoted string literals (see www.sqlite.org/quirks.html#double_quoted_string_literals_are_accepted)

  • :results_as_hash: boolean (default false), return rows as hashes instead of arrays

  • :default_transaction_mode: one of :deferred (default), :immediate, or :exclusive. If a mode is not specified in a call to #transaction, this will be the default transaction mode.



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# File 'lib/sqlite3/database.rb', line 97

def initialize file, options = {}, zvfs = nil
  mode = Constants::Open::READWRITE | Constants::Open::CREATE

  file = file.to_path if file.respond_to? :to_path
  if file.encoding == ::Encoding::UTF_16LE || file.encoding == ::Encoding::UTF_16BE || options[:utf16]
    open16 file
  else
    # The three primary flag values for sqlite3_open_v2 are:
    # SQLITE_OPEN_READONLY
    # SQLITE_OPEN_READWRITE
    # SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE -- always used for sqlite3_open and sqlite3_open16
    mode = Constants::Open::READONLY if options[:readonly]

    if options[:readwrite]
      raise "conflicting options: readonly and readwrite" if options[:readonly]
      mode = Constants::Open::READWRITE
    end

    if options[:flags]
      if options[:readonly] || options[:readwrite]
        raise "conflicting options: flags with readonly and/or readwrite"
      end
      mode = options[:flags]
    end

    open_v2 file.encode("utf-8"), mode, zvfs

    if options[:strict]
      disable_quirk_mode
    end
  end

  @tracefunc = nil
  @authorizer = nil
  @progress_handler = nil
  @collations = {}
  @functions = {}
  @results_as_hash = options[:results_as_hash]
  @readonly = mode & Constants::Open::READONLY != 0
  @default_transaction_mode = options[:default_transaction_mode] || :deferred

  ForkSafety.track(self)

  if block_given?
    begin
      yield self
    ensure
      close
    end
  end
end

Instance Attribute Details

#collations ⇒ Object (readonly)

Returns the value of attribute collations.



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# File 'lib/sqlite3/database.rb', line 45

def collations
  @collations
end

#results_as_hash ⇒ Object

A boolean that indicates whether rows in result sets should be returned as hashes or not. By default, rows are returned as arrays.



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# File 'lib/sqlite3/database.rb', line 77

def results_as_hash
  @results_as_hash
end

Class Method Details

.open(*args) ⇒ Object

Without block works exactly as new. With block, like new closes the database at the end, but unlike new returns the result of the block instead of the database instance.



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# File 'lib/sqlite3/database.rb', line 53

def open(*args)
  database = new(*args)

  if block_given?
    begin
      yield database
    ensure
      database.close
    end
  else
    database
  end
end

.quote(string) ⇒ Object

Quotes the given string, making it safe to use in an SQL statement. It replaces all instances of the single-quote character with two single-quote characters. The modified string is returned.



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# File 'lib/sqlite3/database.rb', line 70

def quote(string)
  string.gsub("'", "''")
end

Instance Method Details

#authorizer(&block) ⇒ Object

Installs (or removes) a block that will be invoked for every access to the database. If the block returns 0 (or nil), the statement is allowed to proceed. Returning 1 causes an authorization error to occur, and returning 2 causes the access to be silently denied.



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# File 'lib/sqlite3/database.rb', line 160

def authorizer(&block)
  self.authorizer = block
end

#set_authorizer=(auth) ⇒ Object

Set the authorizer for this database. auth must respond to call, and call must take 5 arguments.

Installs (or removes) a block that will be invoked for every access to the database. If the block returns 0 (or true), the statement is allowed to proceed. Returning 1 or false causes an authorization error to occur, and returning 2 or nil causes the access to be silently denied.



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# File 'ext/sqlite3/database.c', line 659

static VALUE
set_authorizer(VALUE self, VALUE authorizer)
{
    sqlite3RubyPtr ctx;
    int status;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    status = sqlite3_set_authorizer(
                 ctx->db, NIL_P(authorizer) ? NULL : rb_sqlite3_auth, (void *)self
             );

    CHECK(ctx->db, status);

    rb_iv_set(self, "@authorizer", authorizer);

    return self;
}

#build_result_set(stmt) ⇒ Object

Given a statement, return a result set. This is not intended for general consumption :nodoc:



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# File 'lib/sqlite3/database.rb', line 697

def build_result_set stmt
  if results_as_hash
    HashResultSet.new(self, stmt)
  else
    ResultSet.new(self, stmt)
  end
end

#busy_handler {|count| ... } ⇒ Object #busy_handler(Class.new{) ⇒ Object

Register a busy handler with this database instance. When a requested resource is busy, this handler will be invoked. If the handler returns false, the operation will be aborted; otherwise, the resource will be requested again.

The handler will be invoked with the name of the resource that was busy, and the number of times it has been retried.

See also the mutually exclusive #busy_timeout.

Overloads:

  • #busy_handler {|count| ... } ⇒ Object

    Yields:

    • (count) 


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# File 'ext/sqlite3/database.c', line 313

static VALUE
busy_handler(int argc, VALUE *argv, VALUE self)
{
    sqlite3RubyPtr ctx;
    VALUE block;
    int status;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    rb_scan_args(argc, argv, "01", &block);

    if (NIL_P(block) && rb_block_given_p()) { block = rb_block_proc(); }
    RB_OBJ_WRITE(self, &ctx->busy_handler, block);

    status = sqlite3_busy_handler(
                 ctx->db,
                 NIL_P(block) ? NULL : rb_sqlite3_busy_handler,
                 (void *)ctx
             );

    CHECK(ctx->db, status);

    return self;
}

#busy_handler_timeout=(milliseconds) ⇒ Object

Sets a #busy_handler that releases the GVL between retries, but only retries up to the indicated number of milliseconds. This is an alternative to #busy_timeout, which holds the GVL while SQLite sleeps and retries.



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# File 'lib/sqlite3/database.rb', line 646

def busy_handler_timeout=(milliseconds)
  timeout_seconds = milliseconds.fdiv(1000)

  busy_handler do |count|
    now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    if count.zero?
      @timeout_deadline = now + timeout_seconds
    elsif now > @timeout_deadline
      next false
    else
      sleep(0.001)
    end
  end
end

#busy_timeout=(ms) ⇒ Object Also known as: busy_timeout

Indicates that if a request for a resource terminates because that resource is busy, SQLite should sleep and retry for up to the indicated number of milliseconds. By default, SQLite does not retry busy resources. To restore the default behavior, send 0 as the ms parameter.

See also the mutually exclusive #busy_handler.



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# File 'ext/sqlite3/database.c', line 689

static VALUE
set_busy_timeout(VALUE self, VALUE timeout)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    CHECK(ctx->db, sqlite3_busy_timeout(ctx->db, (int)NUM2INT(timeout)));

    return self;
}

#changes ⇒ Object

Returns the number of changes made to this database instance by the last operation performed. Note that a “delete from table” without a where clause will not affect this value.



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# File 'ext/sqlite3/database.c', line 614

static VALUE
changes(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return INT2NUM(sqlite3_changes(ctx->db));
}

#close ⇒ Object

Close the database and release all associated resources.

⚠ Writable connections that are carried across a fork() are not completely closed. Sqlite does not support forking, and fully closing a writable connection that has been carried across a fork may corrupt the database. Since it is an incomplete close, not all memory resources are freed, but this is safer than risking data loss.

See adr/2024-09-fork-safety.md for more information on fork safety.



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# File 'ext/sqlite3/database.c', line 193

static VALUE
sqlite3_rb_close(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    close_or_discard_db(ctx);

    rb_iv_set(self, "-aggregators", Qnil);

    return self;
}

#closed? ⇒ Boolean

Returns true if this database instance has been closed (see #close).

Returns:

  • (Boolean) 


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# File 'ext/sqlite3/database.c', line 224

static VALUE
closed_p(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    if (!ctx->db) { return Qtrue; }

    return Qfalse;
}

#collation(name, comparator) ⇒ Object

Add a collation with name name, and a comparator object. The comparator object should implement a method called “compare” that takes two parameters and returns an integer less than, equal to, or greater than 0.



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# File 'ext/sqlite3/database.c', line 753

static VALUE
collation(VALUE self, VALUE name, VALUE comparator)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    CHECK(ctx->db, sqlite3_create_collation(
              ctx->db,
              StringValuePtr(name),
              SQLITE_UTF8,
              (void *)comparator,
              NIL_P(comparator) ? NULL : rb_comparator_func));

    /* Make sure our comparator doesn't get garbage collected. */
    rb_hash_aset(rb_iv_get(self, "@collations"), name, comparator);

    return self;
}

#commit ⇒ Object

Commits the current transaction. If there is no current transaction, this will cause an error to be raised. This returns true, in order to allow it to be used in idioms like abort? and rollback or commit.



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# File 'lib/sqlite3/database.rb', line 622

def commit
  execute "commit transaction"
  true
end

#complete?(sql) ⇒ Boolean

Return true if the string is a valid (ie, parsable) SQL statement, and false otherwise.

Returns:

  • (Boolean) 


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# File 'ext/sqlite3/database.c', line 598

static VALUE
complete_p(VALUE UNUSED(self), VALUE sql)
{
    if (sqlite3_complete(StringValuePtr(sql))) {
        return Qtrue;
    }

    return Qfalse;
}

#create_aggregate(name, arity, step = nil, finalize = nil, text_rep = Constants::TextRep::ANY, &block) ⇒ Object

Creates a new aggregate function for use in SQL statements. Aggregate functions are functions that apply over every row in the result set, instead of over just a single row. (A very common aggregate function is the “count” function, for determining the number of rows that match a query.)

The new function will be added as name, with the given arity. (For variable arity functions, use -1 for the arity.)

The step parameter must be a proc object that accepts as its first parameter a FunctionProxy instance (representing the function invocation), with any subsequent parameters (up to the function’s arity). The step callback will be invoked once for each row of the result set.

The finalize parameter must be a proc object that accepts only a single parameter, the FunctionProxy instance representing the current function invocation. It should invoke FunctionProxy#result= to store the result of the function.

Example:

db.create_aggregate( "lengths", 1 ) do
  step do |func, value|
    func[ :total ] ||= 0
    func[ :total ] += ( value ? value.length : 0 )
  end

  finalize do |func|
    func.result = func[ :total ] || 0
  end
end

puts db.get_first_value( "select lengths(name) from table" )

See also #create_aggregate_handler for a more object-oriented approach to aggregate functions.



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# File 'lib/sqlite3/database.rb', line 410

def create_aggregate(name, arity, step = nil, finalize = nil,
  text_rep = Constants::TextRep::ANY, &block)

  proxy = Class.new do
    def self.step(&block)
      define_method(:step_with_ctx, &block)
    end

    def self.finalize(&block)
      define_method(:finalize_with_ctx, &block)
    end
  end

  if block
    proxy.instance_eval(&block)
  else
    proxy.class_eval do
      define_method(:step_with_ctx, step)
      define_method(:finalize_with_ctx, finalize)
    end
  end

  proxy.class_eval do
    # class instance variables
    @name = name
    @arity = arity

    def self.name
      @name
    end

    def self.arity
      @arity
    end

    def initialize
      @ctx = FunctionProxy.new
    end

    def step(*args)
      step_with_ctx(@ctx, *args)
    end

    def finalize
      finalize_with_ctx(@ctx)
      @ctx.result
    end
  end
  define_aggregator2(proxy, name)
end

#create_aggregate_handler(handler) ⇒ Object

This is another approach to creating an aggregate function (see #create_aggregate). Instead of explicitly specifying the name, callbacks, arity, and type, you specify a factory object (the “handler”) that knows how to obtain all of that information. The handler should respond to the following messages:

arity

corresponds to the arity parameter of #create_aggregate. This message is optional, and if the handler does not respond to it, the function will have an arity of -1.

name

this is the name of the function. The handler must implement this message.

new

this must be implemented by the handler. It should return a new instance of the object that will handle a specific invocation of the function.

The handler instance (the object returned by the new message, described above), must respond to the following messages:

step

this is the method that will be called for each step of the aggregate function’s evaluation. It should implement the same signature as the step callback for #create_aggregate.

finalize

this is the method that will be called to finalize the aggregate function’s evaluation. It should implement the same signature as the finalize callback for #create_aggregate.

Example:

class LengthsAggregateHandler
  def self.arity; 1; end
  def self.name; 'lengths'; end

  def initialize
    @total = 0
  end

  def step( ctx, name )
    @total += ( name ? name.length : 0 )
  end

  def finalize( ctx )
    ctx.result = @total
  end
end

db.create_aggregate_handler( LengthsAggregateHandler )
puts db.get_first_value( "select lengths(name) from A" )



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# File 'lib/sqlite3/database.rb', line 508

def create_aggregate_handler(handler)
  # This is a compatibility shim so the (basically pointless) FunctionProxy
  # "ctx" object is passed as first argument to both step() and finalize().
  # Now its up to the library user whether he prefers to store his
  # temporaries as instance variables or fields in the FunctionProxy.
  # The library user still must set the result value with
  # FunctionProxy.result= as there is no backwards compatible way to
  # change this.
  proxy = Class.new(handler) do
    def initialize
      super
      @fp = FunctionProxy.new
    end

    def step(*args)
      super(@fp, *args)
    end

    def finalize
      super(@fp)
      @fp.result
    end
  end
  define_aggregator2(proxy, proxy.name)
  self
end

#create_function(name, arity, text_rep = Constants::TextRep::UTF8, &block) ⇒ Object

Creates a new function for use in SQL statements. It will be added as name, with the given arity. (For variable arity functions, use -1 for the arity.)

The block should accept at least one parameter–the FunctionProxy instance that wraps this function invocation–and any other arguments it needs (up to its arity).

The block does not return a value directly. Instead, it will invoke the FunctionProxy#result= method on the func parameter and indicate the return value that way.

Example:

db.create_function( "maim", 1 ) do |func, value|
  if value.nil?
    func.result = nil
  else
    func.result = value.split(//).sort.join
  end
end

puts db.get_first_value( "select maim(name) from table" )



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# File 'lib/sqlite3/database.rb', line 365

def create_function name, arity, text_rep = Constants::TextRep::UTF8, &block
  define_function_with_flags(name, text_rep) do |*args|
    fp = FunctionProxy.new
    block.call(fp, *args)
    fp.result
  end
  self
end

#define_aggregator(name, aggregator) ⇒ Object

Define an aggregate function named name using a object template object aggregator. aggregator must respond to step and finalize. step will be called with row information and finalize must return the return value for the aggregator function.

_API Change:_ aggregator must also implement clone. The provided aggregator object will serve as template that is cloned to provide the individual instances of the aggregate function. Regular ruby objects already provide a suitable clone. The functions arity is the arity of the step method.



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# File 'lib/sqlite3/database.rb', line 545

def define_aggregator(name, aggregator)
  # Previously, this has been implemented in C. Now this is just yet
  # another compatibility shim
  proxy = Class.new do
    @template = aggregator
    @name = name

    def self.template
      @template
    end

    def self.name
      @name
    end

    def self.arity
      # this is what sqlite3_obj_method_arity did before
      @template.method(:step).arity
    end

    def initialize
      @klass = self.class.template.clone
    end

    def step(*args)
      @klass.step(*args)
    end

    def finalize
      @klass.finalize
    end
  end
  define_aggregator2(proxy, name)
  self
end

#define_function(name) {|args, ...| ... } ⇒ Object

Define a function named name with args. The arity of the block will be used as the arity for the function defined.

Yields:

  • (args, ...) 


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# File 'ext/sqlite3/database.c', line 541

static VALUE
define_function(VALUE self, VALUE name)
{
    return define_function_with_flags(self, name, INT2FIX(SQLITE_UTF8));
}

#define_function_with_flags(name, flags) {|args, ...| ... } ⇒ Object

Define a function named name with args using TextRep bitflags flags. The arity of the block will be used as the arity for the function defined.

Yields:

  • (args, ...) 


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# File 'ext/sqlite3/database.c', line 506

static VALUE
define_function_with_flags(VALUE self, VALUE name, VALUE flags)
{
    sqlite3RubyPtr ctx;
    VALUE block;
    int status;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    block = rb_block_proc();

    status = sqlite3_create_function(
                 ctx->db,
                 StringValuePtr(name),
                 rb_proc_arity(block),
                 NUM2INT(flags),
                 (void *)block,
                 rb_sqlite3_func,
                 NULL,
                 NULL
             );

    CHECK(ctx->db, status);

    rb_hash_aset(rb_iv_get(self, "@functions"), name, block);

    return self;
}

#enable_load_extension(onoff) ⇒ Object

Enable or disable extension loading.



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# File 'ext/sqlite3/database.c', line 803

static VALUE
enable_load_extension(VALUE self, VALUE onoff)
{
    sqlite3RubyPtr ctx;
    int onoffparam;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    if (Qtrue == onoff) {
        onoffparam = 1;
    } else if (Qfalse == onoff) {
        onoffparam = 0;
    } else {
        onoffparam = (int)NUM2INT(onoff);
    }

    CHECK(ctx->db, sqlite3_enable_load_extension(ctx->db, onoffparam));

    return self;
}

#encoding ⇒ Object

call-seq: db.encoding

Fetch the encoding set on this database



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# File 'lib/sqlite3/database.rb', line 152

def encoding
  prepare("PRAGMA encoding") { |stmt| Encoding.find(stmt.first.first) }
end

#errcode ⇒ Object

Return an integer representing the last error to have occurred with this database.



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# File 'ext/sqlite3/database.c', line 583

static VALUE
errcode_(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return INT2NUM(sqlite3_errcode(ctx->db));
}

#errmsg ⇒ Object

Return a string describing the last error to have occurred with this database.



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# File 'ext/sqlite3/database.c', line 568

static VALUE
errmsg(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return rb_str_new2(sqlite3_errmsg(ctx->db));
}

#execute(sql, bind_vars = [], &block) ⇒ Object

Executes the given SQL statement. If additional parameters are given, they are treated as bind variables, and are bound to the placeholders in the query.

Note that if any of the values passed to this are hashes, then the key/value pairs are each bound separately, with the key being used as the name of the placeholder to bind the value to.

The block is optional. If given, it will be invoked for each row returned by the query. Otherwise, any results are accumulated into an array and returned wholesale.

See also #execute2, #query, and #execute_batch for additional ways of executing statements.



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# File 'lib/sqlite3/database.rb', line 201

def execute sql, bind_vars = [], &block
  prepare(sql) do |stmt|
    stmt.bind_params(bind_vars)
    stmt = build_result_set stmt

    if block
      stmt.each do |row|
        yield row
      end
    else
      stmt.to_a.freeze
    end
  end
end

#execute2(sql, *bind_vars) ⇒ Object

Executes the given SQL statement, exactly as with #execute. However, the first row returned (either via the block, or in the returned array) is always the names of the columns. Subsequent rows correspond to the data from the result set.

Thus, even if the query itself returns no rows, this method will always return at least one row–the names of the columns.

See also #execute, #query, and #execute_batch for additional ways of executing statements.



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# File 'lib/sqlite3/database.rb', line 226

def execute2(sql, *bind_vars)
  prepare(sql) do |stmt|
    result = stmt.execute(*bind_vars)
    if block_given?
      yield stmt.columns
      result.each { |row| yield row }
    else
      return result.each_with_object([stmt.columns]) { |row, arr|
               arr << row
             }
    end
  end
end

#execute_batch(sql, bind_vars = []) ⇒ Object

Executes all SQL statements in the given string. By contrast, the other means of executing queries will only execute the first statement in the string, ignoring all subsequent statements. This will execute each one in turn. The same bind parameters, if given, will be applied to each statement.

This always returns the result of the last statement.

See also #execute_batch2 for additional ways of executing statements.



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# File 'lib/sqlite3/database.rb', line 250

def execute_batch(sql, bind_vars = [])
  sql = sql.strip
  result = nil
  until sql.empty?
    prepare(sql) do |stmt|
      unless stmt.closed?
        # FIXME: this should probably use sqlite3's api for batch execution
        # This implementation requires stepping over the results.
        if bind_vars.length == stmt.bind_parameter_count
          stmt.bind_params(bind_vars)
        end
        result = stmt.step
      end
      sql = stmt.remainder.strip
    end
  end

  result
end

#execute_batch2(sql, &block) ⇒ Object

Executes all SQL statements in the given string. By contrast, the other means of executing queries will only execute the first statement in the string, ignoring all subsequent statements. This will execute each one in turn. Bind parameters cannot be passed to #execute_batch2.

If a query is made, all values will be returned as strings. If no query is made, an empty array will be returned.

Because all values except for ‘NULL’ are returned as strings, a block can be passed to parse the values accordingly.

See also #execute_batch for additional ways of executing statements.



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# File 'lib/sqlite3/database.rb', line 283

def execute_batch2(sql, &block)
  if block
    result = exec_batch(sql, @results_as_hash)
    result.map do |val|
      yield val
    end
  else
    exec_batch(sql, @results_as_hash)
  end
end

#extended_result_codes=(true) ⇒ Object

Enable extended result codes in SQLite. These result codes allow for more detailed exception reporting, such a which type of constraint is violated.



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# File 'ext/sqlite3/database.c', line 706

static VALUE
set_extended_result_codes(VALUE self, VALUE enable)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    CHECK(ctx->db, sqlite3_extended_result_codes(ctx->db, RTEST(enable) ? 1 : 0));

    return self;
}

#filename(db_name = "main") ⇒ Object

Returns the filename for the database named db_name. db_name defaults to “main”. Main return ‘nil` or an empty string if the database is temporary or in-memory.



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# File 'lib/sqlite3/database.rb', line 183

def filename db_name = "main"
  db_filename db_name
end

#get_first_row(sql, *bind_vars) ⇒ Object

A convenience method for obtaining the first row of a result set, and discarding all others. It is otherwise identical to #execute.

See also #get_first_value.



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# File 'lib/sqlite3/database.rb', line 322

def get_first_row(sql, *bind_vars)
  execute(sql, *bind_vars).first
end

#get_first_value(sql, *bind_vars) ⇒ Object

A convenience method for obtaining the first value of the first row of a result set, and discarding all other values and rows. It is otherwise identical to #execute.

See also #get_first_row.



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# File 'lib/sqlite3/database.rb', line 331

def get_first_value(sql, *bind_vars)
  query(sql, bind_vars) do |rs|
    if (row = rs.next)
      return @results_as_hash ? row[rs.columns[0]] : row[0]
    end
  end
  nil
end

#interrupt ⇒ Object

Interrupts the currently executing operation, causing it to abort.



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# File 'ext/sqlite3/database.c', line 551

static VALUE
interrupt(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    sqlite3_interrupt(ctx->db);

    return self;
}

#last_insert_row_id ⇒ Object

Obtains the unique row ID of the last row to be inserted by this Database instance.



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# File 'ext/sqlite3/database.c', line 382

static VALUE
last_insert_row_id(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return LL2NUM(sqlite3_last_insert_rowid(ctx->db));
}

#load_extension(file) ⇒ Object

Loads an SQLite extension library from the named file. Extension loading must be enabled using db.enable_load_extension(true) prior to calling this API.



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# File 'ext/sqlite3/database.c', line 780

static VALUE
load_extension(VALUE self, VALUE file)
{
    sqlite3RubyPtr ctx;
    int status;
    char *errMsg;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    status = sqlite3_load_extension(ctx->db, StringValuePtr(file), 0, &errMsg);

    CHECK_MSG(ctx->db, status, errMsg);

    return self;
}

#prepare(sql) ⇒ Object

Returns a Statement object representing the given SQL. This does not execute the statement; it merely prepares the statement for execution.

The Statement can then be executed using Statement#execute.



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# File 'lib/sqlite3/database.rb', line 169

def prepare sql
  stmt = SQLite3::Statement.new(self, sql)
  return stmt unless block_given?

  begin
    yield stmt
  ensure
    stmt.close unless stmt.closed?
  end
end

#query(sql, bind_vars = []) ⇒ Object

This is a convenience method for creating a statement, binding parameters to it, and calling execute:

result = db.query( "select * from foo where a=?", [5])
# is the same as
result = db.prepare( "select * from foo where a=?" ).execute( 5 )

You must be sure to call close on the ResultSet instance that is returned, or you could have problems with locks on the table. If called with a block, close will be invoked implicitly when the block terminates.



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# File 'lib/sqlite3/database.rb', line 305

def query(sql, bind_vars = [])
  result = prepare(sql).execute(bind_vars)
  if block_given?
    begin
      yield result
    ensure
      result.close
    end
  else
    result
  end
end

#readonly? ⇒ Boolean

Returns true if the database has been open in readonly mode A helper to check before performing any operation

Returns:

  • (Boolean) 


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# File 'lib/sqlite3/database.rb', line 638

def readonly?
  @readonly
end

#rollback ⇒ Object

Rolls the current transaction back. If there is no current transaction, this will cause an error to be raised. This returns true, in order to allow it to be used in idioms like abort? and rollback or commit.



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# File 'lib/sqlite3/database.rb', line 631

def rollback
  execute "rollback transaction"
  true
end

#statement_timeout=(ms) ⇒ Object

Indicates that if a query lasts longer than the indicated number of milliseconds, SQLite should interrupt that query and return an error. By default, SQLite does not interrupt queries. To restore the default behavior, send 0 as the ms parameter.



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# File 'ext/sqlite3/database.c', line 363

static VALUE
set_statement_timeout(VALUE self, VALUE milliseconds)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);

    ctx->stmt_timeout = NUM2INT(milliseconds);
    int n = NUM2INT(milliseconds) == 0 ? -1 : 1000;

    sqlite3_progress_handler(ctx->db, n, rb_sqlite3_statement_timeout, (void *)ctx);

    return self;
}

#total_changes ⇒ Object

Returns the total number of changes made to this database instance since it was opened.



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# File 'ext/sqlite3/database.c', line 240

static VALUE
total_changes(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return INT2NUM(sqlite3_total_changes(ctx->db));
}

#trace {|sql| ... } ⇒ Object #trace(Class.new{) ⇒ Object

Installs (or removes) a block that will be invoked for every SQL statement executed. The block receives one parameter: the SQL statement executed. If the block is nil, any existing tracer will be uninstalled.

Overloads:

  • #trace {|sql| ... } ⇒ Object

    Yields:

    • (sql) 


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# File 'ext/sqlite3/database.c', line 266

static VALUE
trace(int argc, VALUE *argv, VALUE self)
{
    sqlite3RubyPtr ctx;
    VALUE block;

    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    rb_scan_args(argc, argv, "01", &block);

    if (NIL_P(block) && rb_block_given_p()) { block = rb_block_proc(); }

    rb_iv_set(self, "@tracefunc", block);

    sqlite3_trace(ctx->db, NIL_P(block) ? NULL : tracefunc, (void *)self);

    return self;
}

#transaction(mode = nil) ⇒ Object

Begins a new transaction. Note that nested transactions are not allowed by SQLite, so attempting to nest a transaction will result in a runtime exception.

The mode parameter may be either :deferred, :immediate, or :exclusive. If ‘nil` is specified, the default transaction mode, which was passed to #initialize, is used.

If a block is given, the database instance is yielded to it, and the transaction is committed when the block terminates. If the block raises an exception, a rollback will be performed instead. Note that if a block is given, #commit and #rollback should never be called explicitly or you’ll get an error when the block terminates.

If a block is not given, it is the caller’s responsibility to end the transaction explicitly, either by calling #commit, or by calling #rollback.



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# File 'lib/sqlite3/database.rb', line 599

def transaction(mode = nil)
  mode = @default_transaction_mode if mode.nil?
  execute "begin #{mode} transaction"

  if block_given?
    abort = false
    begin
      yield self
    rescue
      abort = true
      raise
    ensure
      abort and rollback or commit
    end
  else
    true
  end
end

#transaction_active? ⇒ Boolean

Returns true if there is a transaction active, and false otherwise.

Returns:

  • (Boolean) 


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# File 'ext/sqlite3/database.c', line 830

static VALUE
transaction_active_p(VALUE self)
{
    sqlite3RubyPtr ctx;
    TypedData_Get_Struct(self, sqlite3Ruby, &database_type, ctx);
    REQUIRE_OPEN_DB(ctx);

    return sqlite3_get_autocommit(ctx->db) ? Qfalse : Qtrue;
}