Class: ActiveRecord::ConnectionAdapters::IBM_DBAdapter

Inherits:
AbstractAdapter
  • Object
show all
Defined in:
lib/active_record/connection_adapters/ibm_db_adapter.rb

Overview

The IBM_DB Adapter requires the native Ruby driver (ibm_db) for IBM data servers (ibm_db.so). config the hash passed as an initializer argument content:

mandatory parameters 

adapter:     'ibm_db'        // IBM_DB Adapter name
username:    'db2user'       // data server (database) user
password:    'secret'        // data server (database) password
database:    'ARUNIT'        // remote database name (or catalog entry alias)

optional (highly recommended for data server auditing and monitoring purposes)

schema:      'rails123'      // name space qualifier
account:     'tester'        // OS account (client workstation)
app_user:    'test11'        // authenticated application user
application: 'rtests'        // application name
workstation: 'plato'         // client workstation name

remote TCP/IP connection (required when no local database catalog entry available)

host:        'socrates'      // fully qualified hostname or IP address
port:        '50000'         // data server TCP/IP port number

When schema is not specified, the username value is used instead.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(connection, logger, config, conn_options) ⇒ IBM_DBAdapter

Returns a new instance of IBM_DBAdapter.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 301

def initialize(connection, logger, config, conn_options)
  # Caching database connection configuration (+connect+ or +reconnect+ support)
  @connection = connection
  @conn_options = conn_options
  @database = config[:database]
  @username = config[:username]
  @password = config[:password]
  if config.has_key?(:host)
    @host   = config[:host]
    @port   = config[:port] || 50000 # default port
  end
  @schema   = config[:schema]

  # Caching database connection options (auditing and billing support)
  @app_user    = conn_options[:app_user]     if conn_options.has_key?(:app_user)
  @account     = conn_options[:account]      if conn_options.has_key?(:account)
  @application = conn_options[:application]  if conn_options.has_key?(:application)
  @workstation = conn_options[:workstation]  if conn_options.has_key?(:workstation)

  # Calls the parent class +ConnectionAdapters+' initializer
  # which sets @connection, @logger, @runtime and @last_verification
  super(@connection, logger)

  if @connection
    server_info = IBM_DB::server_info( @connection )
    case server_info.DBMS_NAME
      when /DB2\//i             # DB2 for Linux, Unix and Windows (LUW)
        @servertype = IBM_DB2_LUW.new(self)
      when /DB2/i               # DB2 for zOS
        case server_info.DBMS_VER
          when /09/             # DB2 for zOS version 9
            @servertype = IBM_DB2_ZOS.new(self)
          when /08/             # DB2 for zOS version 8
            @servertype = IBM_DB2_ZOS_8.new(self)
          else                  # DB2 for zOS version 7
            raise "Only DB2 z/OS version 8 and above are currently supported"
        end
      when /AS/i                # DB2 for i5 (iSeries)
        @servertype = IBM_DB2_I5.new(self)
      when /IDS/i               # Informix Dynamic Server
        @servertype = IBM_IDS.new(self)
    end
  end

  # Executes the +set schema+ statement using the schema identifier provided
  @servertype.set_schema(@schema) if @schema && @schema != @username
end

Instance Attribute Details

#account ⇒ Object

Returns the value of attribute account.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 294

def 
  @account
end

#app_user ⇒ Object

Returns the value of attribute app_user.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 294

def app_user
  @app_user
end

#application ⇒ Object

Returns the value of attribute application.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 294

def application
  @application
end

#connection ⇒ Object (readonly)

Returns the value of attribute connection.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 292

def connection
  @connection
end

#schema ⇒ Object

Returns the value of attribute schema.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 294

def schema
  @schema
end

#servertype ⇒ Object (readonly)

Returns the value of attribute servertype.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 292

def servertype
  @servertype
end

#sql ⇒ Object

Returns the value of attribute sql.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 293

def sql
  @sql
end

#workstation ⇒ Object

Returns the value of attribute workstation.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 294

def workstation
  @workstation
end

Instance Method Details

#active? ⇒ Boolean

Tests the connection status

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 416

def active?
  IBM_DB::active @connection
  rescue
    false
end

#adapter_name ⇒ Object

Name of the adapter



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 297

def adapter_name
  'IBM_DB'
end

#add_limit_offset!(sql, options) ⇒ Object

Modifies a sql statement in order to implement a LIMIT and an OFFSET. A LIMIT defines the number of rows that should be fetched, while an OFFSET defines from what row the records must be fetched. IBM data servers implement a LIMIT in SQL statements through: FETCH FIRST n ROWS ONLY, where n is the number of rows required. The implementation of OFFSET is more elaborate, and requires the usage of subqueries and the ROW_NUMBER() command in order to add row numbering as an additional column to a copy of the existing table.

Examples

add_limit_offset!(‘SELECT * FROM staff’, => 10) generates: “SELECT * FROM staff FETCH FIRST 10 ROWS ONLY”

add_limit_offset!(‘SELECT * FROM staff’, => 10, :offset => 30) generates “SELECT O.* FROM (SELECT I.*, ROW_NUMBER() OVER () sys_rownum FROM (SELECT * FROM staff) AS I) AS O WHERE sys_row_num BETWEEN 31 AND 40”



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 597

def add_limit_offset!(sql, options)
  # If there is a limit
  if limit = options[:limit]
    # if the limit is zero
    if limit == 0
      # Returns a query that will always generate zero records
      # (e.g. WHERE sys_row_num BETWEEN 1 and 0)
      sql = @servertype.query_offset_limit(sql, 0, limit)
    # If there is a non-zero limit
    else
      offset = options[:offset]
      # If an offset is specified builds the query with offset and limit,
      # otherwise retrieves only the first +limit+ rows
      sql = @servertype.query_offset_limit(sql, offset, limit)
    end
  end
  # Returns the sql query in any case
  sql
end

#begin_db_transaction ⇒ Object

Begins the transaction (and turns off auto-committing)



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 559

def begin_db_transaction
  # Turns off the auto-commit
  IBM_DB::autocommit(@connection, IBM_DB::SQL_AUTOCOMMIT_OFF)
end

#change_column(table_name, column_name, type, options = {}) ⇒ Object

Changes the column’s definition according to the new options. See TableDefinition#column for details of the options you can use.

Examples
change_column(:suppliers, :name, :string, :limit => 80)
change_column(:accounts, :description, :text)



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 931

def change_column(table_name, column_name, type, options = {})
  @servertype.change_column(table_name, column_name, type, options)
end

#change_column_default(table_name, column_name, default) ⇒ Object

Sets a new default value for a column. This does not set the default value to NULL, instead, it needs DatabaseStatements#execute which can execute the appropriate SQL statement for setting the value.

Examples

change_column_default(:suppliers, :qualification, 'new')
change_column_default(:accounts, :authorized, 1)

Method overriden to satisfy IBM data servers syntax.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 942

def change_column_default(table_name, column_name, default)
  @servertype.change_column_default(table_name, column_name, default)
end

#columns(table_name, name = nil) ⇒ Object

Returns an array of Column objects for the table specified by table_name



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 824

def columns(table_name, name = nil)
  # to_s required because it may be a symbol.
  table_name = @servertype.set_case(table_name.to_s)
  # Checks if a blank table name has been given.
  # If so it returns an empty array
  return [] if table_name.strip.empty?
  # +columns+ will contain the resulting array
  columns = []
  # Statement required to access all the columns information
  if stmt = IBM_DB::columns( @connection, nil, 
                             @servertype.set_case(@schema), 
                             @servertype.set_case(table_name) )
    begin
      # Fetches all the columns and assigns them to col.
      # +col+ is an hash with keys/value pairs for a column
      while col = IBM_DB::fetch_assoc(stmt)
        column_name = col["column_name"].downcase
        # Assigns the column default value.
        column_default_value = col["column_def"]
        # If there is no default value, it assigns NIL
        column_default_value = nil if (column_default_value && column_default_value.upcase == 'NULL')
        # Removes single quotes from the default value
        column_default_value.gsub!(/^'(.*)'$/, '\1') unless column_default_value.nil?
        # Assigns the column type
        column_type = col["type_name"].downcase
        # Assigns the field length (size) for the column
        column_length = col["column_size"]
        column_scale = col["decimal_digits"]
        # The initializer of the class Column, requires the +column_length+ to be declared 
        # between brackets after the datatype(e.g VARCHAR(50)) for :string and :text types. 
        # If it's a "for bit data" field it does a subsitution in place, if not
        # it appends the (column_length) string on the supported data types
        unless column_length.nil? || 
               column_length == '' || 
               column_type.sub!(/ \(\) for bit data/i,"(#{column_length}) FOR BIT DATA") || 
               !column_type =~ /char|lob|graphic/i
          if column_type =~ /decimal/i
            column_type << "(#{column_length},#{column_scale})"
          elsif column_type =~ /smallint|integer|double|date|time|timestamp|xml/i
            column_type << ""  # override native limits incompatible with table create
          else
            column_type << "(#{column_length})"
          end
        end
        # col["NULLABLE"] is 1 if the field is nullable, 0 if not.
        column_nullable = (col["nullable"] == 1) ? true : false
        # Make sure the hidden column (db2_generated_rowid_for_lobs) in DB2 z/OS isn't added to the list
        if !(column_name =~ /db2_generated_rowid_for_lobs/i)
          # Pushes into the array the *IBM_DBColumn* object, created by passing to the initializer
          # +column_name+, +default_value+, +column_type+ and +column_nullable+.
          columns << IBM_DBColumn.new(column_name, column_default_value, column_type, column_nullable)
        end
      end
    rescue StandardError  # Handle driver fetch errors
      error_msg = IBM_DB::conn_errormsg ? IBM_DB::conn_errormsg : IBM_DB::stmt_errormsg
      if error_msg && !error_msg.empty?
        raise "Failed to retrieve column metadata during fetch: #{error_msg}"
      else
        raise
      end
    ensure  # Free resources associated with the statement
      IBM_DB::free_result(stmt)
    end
  else  # Handle driver execution errors
    error_msg = IBM_DB::conn_errormsg ? IBM_DB::conn_errormsg : IBM_DB::stmt_errormsg
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve column metadata due to error: #{error_msg}"
    else
      raise StandardError('Unexpected error during columns metadata retrieval')
    end
  end
  # Returns the columns array
  return columns
end

#commit_db_transaction ⇒ Object

Commits the transaction and turns on auto-committing



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 565

def commit_db_transaction
  # Commits the transaction
  IBM_DB::commit @connection rescue nil
  # Turns on auto-committing
  IBM_DB::autocommit @connection, IBM_DB::SQL_AUTOCOMMIT_ON
end

#create_table(name, options = {}) ⇒ Object

DATABASE STATEMENTS



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 466

def create_table(name, options = {})
  @servertype.setup_for_lob_table
  super
  # force implicit id column (primary key) unless :id => false
  unless !options[:id].nil? and
         !options[:id]
    @servertype.create_index_after_table(name)
  end
end

#default_sequence_name(table, column) ⇒ Object

method add_limit_offset!



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 617

def default_sequence_name(table, column) # :nodoc:
  "#{table}_#{column}_seq"
end

#disconnect! ⇒ Object

Closes the current connection



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 454

def disconnect!
  # Attempts to close the connection. The methods will return:
  # * true if succesfull
  # * false if the connection is already closed
  # * nil if an error is raised
  IBM_DB::close(@connection) rescue nil
end

#execute(sql, name = nil) ⇒ Object

Executes and logs sql commands and returns a IBM_DB::Statement object.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 523

def execute(sql, name = nil)
  # Logs and execute the sql instructions.
  # The +log+ method is defined in the parent class +AbstractAdapter+
  log(sql, name) do
    @servertype.execute(sql, name)
  end
end

#indexes(table_name, name = nil) ⇒ Object

Returns an array of non-primary key indexes for a specified table name



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 778

def indexes(table_name, name = nil)
  # to_s required because +table_name+ may be a symbol.
  table_name = table_name.to_s
  # Checks if a blank table name has been given.
  # If so it returns an empty array of columns.
  return [] if table_name.strip.empty?

  # +indexes+ will contain the resulting array
  indexes = []
  # Query table statistics for all indexes on the table
  # "TABLE_NAME:   #{index_stats[2]}"
  # "NON_UNIQUE:   #{index_stats[3]}"
  # "INDEX_NAME:   #{index_stats[5]}"
  # "COLUMN_NAME:  #{index_stats[8]}"
  if stmt = IBM_DB::statistics( @connection, nil, 
                                @servertype.set_case(@schema), 
                                @servertype.set_case(table_name), 1 )
    begin
      while ( index_stats = IBM_DB::fetch_array(stmt) )
        if index_stats[5]                                          # INDEX_NAME
          index_name = index_stats[5].downcase
          # Non-unique index type (not the primary key)
          unless index_stats[3] == 0                               # NON_UNIQUE
            index_unique = (index_stats[3] == 0)
            index_columns = index_stats[8].map{|c| c.downcase}     # COLUMN_NAME
            # Create an IndexDefinition object and add to the indexes array
            indexes << IndexDefinition.new(table_name, index_name, index_unique, index_columns)
          end
        end
      end
    ensure  # Free resources associated with the statement
      IBM_DB::free_result(stmt) if stmt
    end
  else  # Handle driver execution errors
    error_msg = IBM_DB::conn_errormsg ? IBM_DB::conn_errormsg : IBM_DB::stmt_errormsg
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve index metadata due to error: #{error_msg}"
    else
      raise StandardError('Unexpected error during index retrieval')
    end
  end
  # Returns the indexes array
  return indexes
end

#insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) ⇒ Object

Perform an insert and returns the last ID generated. This can be the ID passed to the method or the one auto-generated by the database, and retrieved by the last_generated_id method.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 509

def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
  if stmt = execute(sql, name)
    begin
      @sql = sql
      return id_value || @servertype.last_generated_id(stmt)
      # Ensures to free the resources associated with the statement
    ensure
      IBM_DB::free_result(stmt)
    end
  end
end

#log_query(sql, name) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 406

def log_query(sql, name) #:nodoc:
  # Used by handle_lobs
  log(sql,name){}
end

#native_database_types ⇒ Object

Returns a Hash of mappings from the abstract data types to the native database types



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 704

def native_database_types
  {
    :primary_key => @servertype.primary_key,
    :string      => { :name => "varchar", :limit => 255 },
    :text        => { :name => "clob" },
    :integer     => { :name => "integer" },
    :float       => { :name => "float" },
    :datetime    => { :name => @servertype.get_datetime_mapping },
    :timestamp   => { :name => @servertype.get_datetime_mapping },
    :time        => { :name => @servertype.get_time_mapping },
    :date        => { :name => "date" },
    :binary      => { :name => "blob" },

    # IBM data servers don't have a native boolean type.
    # A boolean can be represented  by a smallint,
    # adopting the convention that False is 0 and True is 1
    :boolean     => { :name => "smallint"},
    :xml         => { :name => "xml"},
    :decimal     => { :name => "decimal" },
    :rowid       => { :name => "rowid" }, # rowid is a supported datatype on z/OS and i/5
    :serial      => { :name => "serial" } # rowid is a supported datatype on Informix Dynamic Server
  }
end

#quote(value, column = nil) ⇒ Object

Properly quotes the various data types. value contains the data, column is optional and contains info on the field



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 628

def quote(value, column = nil)
  case value
    # If it's a numeric value and the column type is not a string, it shouldn't be quoted
    # (IBM_DB doesn't accept quotes on numeric types)
    when Numeric
      # If the column type is text or string, return the quote value
      if column && column.type == :text || column && column.type == :string
        "'#{value}'"
      else
        # value is Numeric, column.type is not a string,
        # therefore it converts the number to string without quoting it
        value.to_s
      end
    when String, ActiveSupport::Multibyte::Chars
    if column && column.type == :binary
      # If quoting is required for the insert/update of a BLOB
      unless caller[0] =~ /add_column_options/i
        # Invokes a convertion from string to binary
          @servertype.set_binary_value
      else
        # Quoting required for the default value of a column
          @servertype.set_binary_default(value)
        end
    elsif column && column.type == :text
        unless caller[0] =~ /add_column_options/i
          "'@@@IBMTEXT@@@'"
        else
          @servertype.set_text_default(value)
        end
    elsif column && column.type == :xml
        unless caller[0] =~ /add_column_options/i
          "'<ibm>@@@IBMXML@@@</ibm>'"
        else
          "#{value}"
        end
    else
      "'#{quote_string(value)}'"
    end
    when TrueClass then quoted_true    # return '1' for true
    when FalseClass then quoted_false  # return '0' for false
    when NilClass
      if column && column.instance_of?(IBM_DBColumn) && !column.primary && !column.null
        "''"                           # allow empty inserts if not nullable or identity
      else                             # in order to support default ActiveRecord constructors
        "NULL"
      end
    else super                         # rely on superclass handling
  end
end

#quote_column_name(name) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 694

def quote_column_name(name)
   @servertype.check_reserved_words(name)
end

#quote_string(string) ⇒ Object

Quotes a given string, escaping single quote (‘) characters.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 679

def quote_string(string)
  string.gsub(/'/, "''")
end

#quoted_false ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 690

def quoted_false
  "0"
end

#quoted_true ⇒ Object

true is represented by a smallint 1, false by 0, as no native boolean type exists in DB2. Numerics are not quoted in DB2.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 686

def quoted_true
  "1"
end

#reconnect! ⇒ Object

Closes the current connection and opens a new one



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 448

def reconnect!
  disconnect!
  connect
end

#remove_column(table_name, column_name) ⇒ Object

Removes the column from the table definition.

Examples
remove_column(:suppliers, :qualification)



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 922

def remove_column(table_name, column_name)
  @servertype.remove_column(table_name, column_name)
end

#remove_index(table_name, options = {}) ⇒ Object

Remove the given index from the table.

Remove the suppliers_name_index in the suppliers table (legacy support, use the second or third forms).

remove_index :suppliers, :name

Remove the index named accounts_branch_id in the accounts table.

remove_index :accounts, :column => :branch_id

Remove the index named by_branch_party in the accounts table.

remove_index :accounts, :name => :by_branch_party

You can remove an index on multiple columns by specifying the first column.

add_index :accounts, [:username, :password]
remove_index :accounts, :username

Overriden to use the IBM data servers SQL syntax.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 959

def remove_index(table_name, options = {})
  execute("DROP INDEX #{index_name(table_name, options)}")
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object

Renames a column.

Example
rename_column(:suppliers, :description, :name)



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 915

def rename_column(table_name, column_name, new_column_name)
  @servertype.rename_column(table_name, column_name, new_column_name)
end

#rename_table(name, new_name) ⇒ Object

Renames a table.

Example

rename_table(‘octopuses’, ‘octopi’) Overriden to satisfy IBM data servers syntax



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 903

def rename_table(name, new_name)
  # SQL rename table statement
  rename_table_sql = "RENAME TABLE #{name} TO #{new_name}"
  stmt = execute(rename_table_sql)
  # Ensures to free the resources associated with the statement
  ensure
    IBM_DB::free_result stmt if stmt
end

#rollback_db_transaction ⇒ Object

Rolls back the transaction and turns on auto-committing. Must be done if the transaction block raises an exception or returns false



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 574

def rollback_db_transaction
  # ROLLBACK the transaction
  IBM_DB::rollback(@connection) rescue nil
  # Turns on auto-committing
  IBM_DB::autocommit @connection, IBM_DB::SQL_AUTOCOMMIT_ON
end

#select_all(sql, name = nil) ⇒ Object

Returns an array of hashes with the column names as keys and column values as values. sql is the select query, and name is an optional description for logging



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 479

def select_all(sql, name = nil)
  # Replaces {"= NULL" with " IS NULL"} OR {"IN (NULL)" with " IS NULL"}
  sql.gsub!( /(=\s*NULL|IN\s*\(NULL\))/i, " IS NULL" )
  
  results = []
  # Invokes the method +execute+ in order to log and execute the SQL
  # IBM_DB::Statement is returned from which results can be fetched
  if stmt = execute(sql, name)
    begin
      @servertype.select_all(sql, name, stmt, results)
    ensure
      # Ensures to free the resources associated with the statement
      IBM_DB::free_result stmt
    end
  end
  # The array of record hashes is returned
  results
end

#select_one(sql, name = nil) ⇒ Object

Returns a record hash with the column names as keys and column values as values.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 500

def select_one(sql, name = nil)
  # Gets the first hash from the array of hashes returned by
  # select_all
  select_all(sql,name).first
end

#supports_migrations? ⇒ Boolean

This adapter supports migrations. Current limitations: rename_column is not currently supported by the IBM data servers remove_column is not currently supported by the DB2 for zOS data server Tables containing columns of XML data type do not support remove_column

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 402

def supports_migrations?
  true
end

#table_alias_length ⇒ Object

Returns the maximum length a table alias identifier can be. IBM data servers (cross-platform) table limit is 128 characters



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 745

def table_alias_length
  128
end

#tables(name = nil) ⇒ Object

Retrieves table’s metadata for a specified shema name



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 750

def tables(name = nil)
  # Initializes the tables array
  tables = []
  # Retrieve table's metadata through IBM_DB driver
  if stmt = IBM_DB::tables(@connection, nil, 
                           @servertype.set_case(@schema))
    begin
      # Fetches all the records available
      while tab = IBM_DB::fetch_assoc(stmt)
        # Adds the lowercase table name to the array
        tables << tab["table_name"].downcase
      end
    ensure
      IBM_DB::free_result(stmt)  # Free resources associated with the statement
    end
  else # Handle driver execution errors
    error_msg = IBM_DB::conn_errormsg ? IBM_DB::conn_errormsg : IBM_DB::stmt_errormsg
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve tables metadata due to error: #{error_msg}"
    else
      raise StandardError('Unexpected error during table metadata retrieval')
    end
  end
  # Returns the tables array
  return tables
end

#type_to_sql(type, limit = nil, precision = nil, scale = nil) ⇒ Object

IBM data servers do not support limits on certain data types (unlike MySQL) Limit is supported for the decimal, numeric, varchar, clob, blob data types.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 730

def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  return super if limit.nil?

  # strip off limits on data types not supporting them
  if [:integer, :double, :date, :time, :timestamp, :xml].include? type
    return type.to_s
  elsif type.to_sym == :boolean
    return "smallint"
  else
    return super
  end
end

#update(sql, name = nil) ⇒ Object Also known as: delete

Executes an “UPDATE” SQL statement



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 532

def update(sql, name = nil)
  # Make sure the WHERE clause handles NULL's correctly
  sqlarray = sql.split(/\s*WHERE\s*/)
  if !sqlarray[1].nil?
    sqlarray[1].gsub!( /(=\s*NULL|IN\s*\(NULL\))/i, " IS NULL" )
    sql = sqlarray[0] + " WHERE " + sqlarray[1]
  end

  # Logs and execute the given sql query.
  if stmt = execute(sql, name)
    begin
      @sql = sql
      # Retrieves the number of affected rows
      IBM_DB::num_rows(stmt)
      # Ensures to free the resources associated with the statement
    ensure
      IBM_DB::free_result(stmt)
    end
  end
end