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
security:        'SSL'           // optional parameter enabling SSL encryption -
                                 // - Available only from CLI version V95fp2 and above
authentication:  'SERVER'        // AUTHENTICATION type which the client uses - 
                                 // - to connect to the database server. By default value is SERVER
timeout:         10              // Specifies the time in seconds (0 - 32767) to wait for a reply from server -
                                 //- when trying to establish a connection before generating a timeout

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 415

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]
  @security         = config[:security] || nil
  @authentication   = config[:authentication] || nil
  @timeout          = config[:timeout] || 0  # default timeout value is 0
  
  # 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)
  
  @sql = []
  @handle_lobs_triggered = false

  # 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 )
    if( server_info )
      case server_info.DBMS_NAME
        when /DB2\//i             # DB2 for Linux, Unix and Windows (LUW)
          case server_info.DBMS_VER
            when /09.07/i          # DB2 Version 9.7 (Cobra)
              @servertype = IBM_DB2_LUW_COBRA.new(self)
            else                  # DB2 Version 9.5 or below
              @servertype = IBM_DB2_LUW.new(self)
          end
        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)
        else
          log( "server_info", "Forcing servertype to LUW: DBMS name could not be retrieved. Check if your client version is of the right level")
          warn "Forcing servertype to LUW: DBMS name could not be retrieved. Check if your client version is of the right level"
          @servertype = IBM_DB2_LUW.new(self)
      end
    else
      error_msg = IBM_DB.getErrormsg( @connection, IBM_DB::DB_CONN )
      IBM_DB.close( @connection )
      raise "Cannot retrieve server information: #{error_msg}"
    end
  end

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

  # Check for the start value for id (primary key column). By default it is 1
  if config.has_key?(:start_id)
    @start_id = config[:start_id]
  else
    @start_id = 1
  end
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 408

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 408

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 408

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 406

def connection
  @connection
end

#handle_lobs_triggered ⇒ Object

Returns the value of attribute handle_lobs_triggered.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 407

def handle_lobs_triggered
  @handle_lobs_triggered
end

#schema ⇒ Object

Returns the value of attribute schema.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 408

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 406

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 407

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 408

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 565

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 411

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 888

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 850

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 1363

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 1400

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

#change_column_null(table_name, column_name, null, default = nil) ⇒ Object

Changes the nullability value of a column



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1405

def change_column_null(table_name, column_name, null, default = nil)
  @servertype.change_column_null(table_name, column_name, null, 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 1253

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
  stmt = IBM_DB.columns( @connection, nil, 
                             @servertype.set_case(@schema), 
                             @servertype.set_case(table_name) )
  if(stmt)
    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 => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(stmt, IBM_DB::DB_STMT )
      if error_msg && !error_msg.empty?
        raise "Failed to retrieve column metadata during fetch: #{error_msg}"
      else
        error_msg = "An unexpected error occurred during retrieval of column metadata"
        error_msg = error_msg + ": #{fetch_error.message}" if !fetch_error.message.empty?
        raise error_msg
      end
    ensure  # Free resources associated with the statement
      IBM_DB.free_result(stmt)
    end
  else  # Handle driver execution errors
    error_msg = IBM_DB.getErrormsg(@connection, IBM_DB::DB_CONN )
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve column metadata due to error: #{error_msg}"
    else
      raise StandardError.new('An unexpected error occurred during retrieval of columns metadata')
    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 856

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 624

def create_table(name, options = {})
  @servertype.setup_for_lob_table
  super
  
  #Table definition is complete only when a unique index is created on the primarykey column for DB2 V8 on zOS
  
  #create index on id column if options[:id] is nil or id ==true
  #else check if options[:primary_key]is not nil then create an unique index on that column
  if  !options[:id].nil? || !options[:primary_key].nil?
    if (!options[:id].nil? && options[:id] == true)
      @servertype.create_index_after_table(name,"id")
    elsif !options[:primary_key].nil?
      @servertype.create_index_after_table(name,options[:primary_key].to_s)
    end
  else
    @servertype.create_index_after_table(name,"id")
  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 908

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 612

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 799

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 1132

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 = []
  pk_index = nil
  index_schema = []
  
  #fetch the primary keys of the table using function primary_keys
  #TABLE_SCHEM:: pk_index[1]
  #TABLE_NAME:: pk_index[2]
  #COLUMN_NAME:: pk_index[3]
  #PK_NAME:: pk_index[5]
  stmt = IBM_DB.primary_keys( @connection, nil, 
                             @servertype.set_case(@schema), 
                             @servertype.set_case(table_name))
  if(stmt)
    begin
      while ( pk_index_row = IBM_DB.fetch_array(stmt) )
        if pk_index_row[5] 
          pk_index_name = pk_index_row[5].downcase
          pk_index_columns = [pk_index_row[3].downcase]           # COLUMN_NAME
          if pk_index 
            pk_index.columns = pk_index.columns + pk_index_columns
          else
            pk_index = IndexDefinition.new(table_name, pk_index_name, true, pk_index_columns)
          end
        end 
      end
    rescue StandardError => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(stmt, IBM_DB::DB_STMT )
      if error_msg && !error_msg.empty?
        raise "Failed to retrieve primarykey metadata during fetch: #{error_msg}"
      else
        error_msg = "An unexpected error occurred during retrieval of primary key metadata"
        error_msg = error_msg + ": #{fetch_error.message}" if !fetch_error.message.empty?
        raise error_msg
      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.getErrormsg(@connection, IBM_DB::DB_CONN )
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve primary key metadata due to error: #{error_msg}"
    else
      raise StandardError.new('An unexpected error occurred during primary key retrieval')
    end
  end

  # 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]}"
  stmt = IBM_DB.statistics( @connection, nil, 
                            @servertype.set_case(@schema), 
                            @servertype.set_case(table_name), 1 )
  if(stmt)
    begin
      while ( index_stats = IBM_DB.fetch_array(stmt) )
          is_composite = false
        if index_stats[5]             # INDEX_NAME
          index_name = index_stats[5].downcase
          index_unique = (index_stats[3] == 0)
          index_columns = [index_stats[8].downcase]     # COLUMN_NAME
          index_qualifier = index_stats[4].downcase             #Index_Qualifier
          # Create an IndexDefinition object and add to the indexes array
          i = 0;
          indexes.each do |index|
            if index.name == index_name && index_schema[i] == index_qualifier
               index.columns = index.columns + index_columns
               is_composite = true
            end 
            i = i+1
          end
        
          unless is_composite 
            indexes << IndexDefinition.new(table_name, index_name, index_unique, index_columns)
            index_schema << index_qualifier
          end 
        end
      end
    rescue StandardError => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(stmt, IBM_DB::DB_STMT )
      if error_msg && !error_msg.empty?
        raise "Failed to retrieve index metadata during fetch: #{error_msg}"
      else
        error_msg = "An unexpected error occurred during retrieval of index metadata"
        error_msg = error_msg + ": #{fetch_error.message}" if !fetch_error.message.empty?
        raise error_msg
      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.getErrormsg(@connection, IBM_DB::DB_CONN )
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve index metadata due to error: #{error_msg}"
    else
      raise StandardError.new('An unexpected error occurred during index retrieval')
    end
  end
    
  # remove the primary key index entry.... should not be dumped by the dumper
    
  i = 0
  indexes.each do |index|
    if pk_index && index.columns == pk_index.columns
      indexes.delete_at(i)
    end
    i = i+1
  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 778

def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
  if @handle_lobs_triggered  #Ensure the array of sql is cleared if they have been handled in the callback
    @sql = []
    @handle_lobs_triggered = false
  end

  clear_query_cache if defined? clear_query_cache

  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

#insert_fixture(fixture, table_name) ⇒ Object

inserts values from fixtures overridden to handle LOB’s fixture insertion, as, in normal inserts callbacks are triggered but during fixture insertion callbacks are not triggered hence only markers like @@@IBMBINARY@@@ will be inserted and are not updated to actual data



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 718

def insert_fixture(fixture, table_name)
  insert_query = "INSERT INTO #{quote_table_name(table_name)} ( #{fixture.key_list})"
  insert_values = []
  params = []
  if @servertype.instance_of? IBM_IDS
    super
    return
  end
  column_list = columns(table_name)
  fixture.each do |item|
    col = nil
    column_list.each do |column|
      if column.name.downcase == item.at(0).downcase
        col= column
        break
      end
    end
    if item.at(1).nil? || 
        item.at(1) == {} || 
        (item.at(1) == '' && !(col.type.to_sym == :text))
    
          params << 'NULL'
    
    elsif col.type.to_sym == :xml ||
           col.type.to_sym == :text ||
              col.type.to_sym == :binary 
      #  Add a '?' for the parameter or a NULL if the value is nil or empty 
      # (except for a CLOB field where '' can be a value)
       insert_values << item.at(1)
       params << '?'
    else
      insert_values << quote(item.at(1),col)
      params << '?'
    end 
  end
    
  insert_query << " VALUES ("+ params.join(',') + ")"
  unless stmt = IBM_DB.prepare(@connection, insert_query)
     error_msg = IBM_DB.getErrormsg( @connection, IBM_DB::DB_CONN )
     if error_msg && !error_msg.empty?
       raise "Failed to prepare statement for fixtures insert due to : #{error_msg}"
     else
       raise StandardError.new('An unexpected error occurred during preparing SQL for fixture insert')
     end
  end
    
  #log_query(insert_query,'fixture insert')
  log(insert_query,'fixture insert') do
    unless IBM_DB.execute(stmt, insert_values)
      error_msg = IBM_DB.getErrormsg(stmt, IBM_DB::DB_STMT )
      raise "Failed to insert due to: #{error_msg}"
    else
      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 555

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 1003

def native_database_types
  {
    :primary_key => { :name => @servertype.primary_key_definition(@start_id)},
    :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
    :char        => { :name => "char" },
    :double      => { :name => @servertype.get_double_mapping },
    :decfloat    => { :name => "decfloat"}
  }
end

#primary_key(table_name) ⇒ Object

Returns the primary key of the mentioned table



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1098

def primary_key(table_name)
  pk_name = nil
  stmt = IBM_DB.primary_keys( @connection, nil, 
                              @servertype.set_case(@schema), 
                              @servertype.set_case(table_name))
  if(stmt) 
    begin
      if ( pk_index_row = IBM_DB.fetch_array(stmt) )
        pk_name = pk_index_row[3].downcase
      end
    rescue StandardError => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg( stmt, IBM_DB::DB_STMT )
      if error_msg && !error_msg.empty?
        raise "Failed to retrieve primarykey metadata during fetch: #{error_msg}"
      else
        error_msg = "An unexpected error occurred during retrieval of primary key metadata"
        error_msg = error_msg + ": #{fetch_error.message}" if !fetch_error.message.empty?
        raise error_msg
      end
    ensure  # Free resources associated with the statement
      IBM_DB.free_result(stmt) if stmt
    end
  else
    error_msg = IBM_DB.getErrormsg( @connection, IBM_DB::DB_CONN )
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve primary key metadata due to error: #{error_msg}"
    else
      raise StandardError.new('An unexpected error occurred during primary key retrieval')
    end
  end
  return pk_name
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 919

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.to_sym == :text || column && column.type.to_sym == :string
        unless caller[0] =~ /insert_fixture/i
            "'#{value}'"
        else
            "#{value}"
        end 
      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.to_sym == :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.to_sym == :text
        unless caller[0] =~ /add_column_options/i
          "'@@@IBMTEXT@@@'"
        else
          @servertype.set_text_default(quote_string(value))
        end
    elsif column && column.type.to_sym == :xml
        unless caller[0] =~ /add_column_options/i
          "'<ibm>@@@IBMXML@@@</ibm>'"
        else
          "#{value}"
        end
    else
        unless caller[0] =~ /insert_fixture/i
          "'#{quote_string(value)}'"
        else
          "#{value}"
        end 
    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 993

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 978

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 989

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 985

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 606

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 1354

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 1422

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 1347

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 1335

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 865

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(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 646

def select(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
  stmt = execute(sql, name)
  if(stmt)
    begin
      @servertype.select(sql, name, stmt, results)
    rescue StandardError => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(stmt, IBM_DB::DB_STMT )
      if error_msg && !error_msg.empty?
        raise StatementInvalid,"Failed to retrieve data: #{error_msg}"
      else
        error_msg = "An unexpected error occurred during data retrieval"
        error_msg = error_msg + ": #{fetch_error.message}" if !fetch_error.message.empty?
        raise error_msg
      end
    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 709

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

#select_rows(sql, name = nil) ⇒ Object

Returns an array of arrays containing the field values. This is an implementation for the abstract method 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 678

def select_rows(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
  stmt = execute(sql, name)
  if(stmt)
    begin
      @servertype.select_rows(sql, name, stmt, results)
    rescue StandardError => fetch_error  # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(stmt, IBM_DB::DB_STMT )
      if error_msg && !error_msg.empty?
        raise StatementInvalid,"Failed to retrieve data: #{error_msg}"
      else
        error_msg = "An unexpected error occurred during data retrieval"
        error_msg = error_msg + ": #{fetch_error.message}" if !fetch_error.message.empty?
        raise error_msg
      end
    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

#supports_ddl_transactions? ⇒ Boolean

This Adapter supports DDL transactions. This means CREATE TABLE and other DDL statements can be carried out as a transaction. That is the statements executed can be ROLLED BACK in case of any error during the process.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 551

def supports_ddl_transactions?
  true
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 544

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 1053

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 1058

def tables(name = nil)
  # Initializes the tables array
  tables = []
  # Retrieve table's metadata through IBM_DB driver
  stmt = IBM_DB.tables(@connection, nil, 
                      @servertype.set_case(@schema))
  if(stmt)
    begin
      # Fetches all the records available
      while tab = IBM_DB.fetch_assoc(stmt)
        # Adds the lowercase table name to the array
        if(tab["table_type"]== 'TABLE')  #check, so that only tables are dumped,IBM_DB.tables also returns views,alias etc in the schema
          tables << tab["table_name"].downcase    
        end
      end
    rescue StandardError => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(stmt, IBM_DB::DB_STMT )
      if error_msg && !error_msg.empty?
        raise "Failed to retrieve table metadata during fetch: #{error_msg}"
      else
        error_msg = "An unexpected error occurred during retrieval of table metadata"
        error_msg = error_msg + ": #{fetch_error.message}" if !fetch_error.message.empty?
        raise error_msg
      end
    ensure
      IBM_DB.free_result(stmt)  # Free resources associated with the statement
    end
  else # Handle driver execution errors
    error_msg = IBM_DB.getErrormsg(@connection, IBM_DB::DB_CONN )
    if error_msg && !error_msg.empty?
      raise "Failed to retrieve tables metadata due to error: #{error_msg}"
    else
      raise StandardError.new('An unexpected error occurred during retrieval of table metadata')
    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 1032

def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  if type.to_sym == :decfloat
    sql_segment = native_database_types[type.to_sym][:name].to_s
    sql_segment << "(#{precision})" if !precision.nil?
    return sql_segment
  end
  
  return super if limit.nil?

  # strip off limits on data types not supporting them
  if @servertype.limit_not_supported_types.include? type.to_sym
    return native_database_types[type.to_sym][:name].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 808

def update(sql, name = nil)
  if @handle_lobs_triggered  #Ensure the array of sql is cleared if they have been handled in the callback
    @sql = []
    @handle_lobs_triggered = false
  end

  clear_query_cache if defined? clear_query_cache
  
  # Make sure the WHERE clause handles NULL's correctly
  sqlarray = sql.split(/\s*WHERE\s*/)
  size = sqlarray.size
  if size > 1
    sql = sqlarray[0] + " WHERE "
    if size > 2
      1.upto size-2 do |index|
        sqlarray[index].gsub!( /(=\s*NULL|IN\s*\(NULL\))/i, " IS NULL" ) unless sqlarray[index].nil?
        sql = sql + sqlarray[index] + " WHERE "
      end
    end
    sqlarray[size-1].gsub!( /(=\s*NULL|IN\s*\(NULL\))/i, " IS NULL" ) unless sqlarray[size-1].nil?
    sql = sql + sqlarray[size-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