Class: ActiveRecord::ConnectionAdapters::IBM_DBAdapter

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

Parameterized Queries Support

parameterized:  false            // Specifies if the prepared statement support of 
                                 //- the IBM_DB Adapter is to be turned on or off

When schema is not specified, the username value is used instead. The default setting of parameterized is false.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from QueryCache

included, #prepared_select_with_query_cache

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 476

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

  if( config.has_key?(:parameterized) && config[:parameterized] == true )
    @pstmt_support_on = true
    @set_quoted_literal_replacement = IBM_DB::QUOTED_LITERAL_REPLACEMENT_OFF
  else
    @pstmt_support_on = false
    @set_quoted_literal_replacement = IBM_DB::QUOTED_LITERAL_REPLACEMENT_ON
  end
  
  @app_user = @account = @application = @workstation = nil
  # 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                  = []
  @sql_parameter_values = [] #Used only if pstmt support is turned on

  @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/ || /10/             # DB2 for zOS version 9 and version 10
              @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 468

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 468

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 468

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 466

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 467

def handle_lobs_triggered
  @handle_lobs_triggered
end

#pstmt_support_on ⇒ Object (readonly)

Returns the value of attribute pstmt_support_on.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 469

def pstmt_support_on
  @pstmt_support_on
end

#schema ⇒ Object

Returns the value of attribute schema.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 468

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 466

def servertype
  @servertype
end

#set_quoted_literal_replacement ⇒ Object (readonly)

Returns the value of attribute set_quoted_literal_replacement.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 469

def set_quoted_literal_replacement
  @set_quoted_literal_replacement
end

#sql ⇒ Object

Returns the value of attribute sql.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 467

def sql
  @sql
end

#sql_parameter_values ⇒ Object

Returns the value of attribute sql_parameter_values.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 467

def sql_parameter_values
  @sql_parameter_values
end

#workstation ⇒ Object

Returns the value of attribute workstation.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 468

def workstation
  @workstation
end

Class Method Details

.visitor_for(pool) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 611

def self.visitor_for(pool)
  Arel::Visitors::IBM_DB.new(pool)
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 650

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 472

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 1214

def add_limit_offset!(sql, options)
  limit = options[:limit]
  offset = options[:offset]

  # if the limit is zero
  if limit && limit == 0
    # Returns a query that will always generate zero records
    # (e.g. WHERE sys_row_num BETWEEN 1 and 0)
    if( @pstmt_support_on )
      sql = @servertype.query_offset_limit!(sql, 0, limit, options)
    else
      sql = @servertype.query_offset_limit(sql, 0, limit)
    end
  # If there is a non-zero limit
  else
    # If an offset is specified builds the query with offset and limit,
    # otherwise retrieves only the first +limit+ rows
    if( @pstmt_support_on )
      sql = @servertype.query_offset_limit!(sql, offset, limit, options)
    else
      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 1176

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

#build_conn_str_for_dbops ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1400

def build_conn_str_for_dbops()
  connect_str = "DRIVER={IBM DB2 ODBC DRIVER};ATTACH=true;"
  if(!@host.nil?)
    connect_str << "HOSTNAME=#{@host};"
    connect_str << "PORT=#{@port};"
    connect_str << "PROTOCOL=TCPIP;"
  end
  connect_str << "UID=#{@username};PWD=#{@password};"
  return connect_str
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 1792

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 1838

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 1843

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 1680

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')
        # If default value is IDENTITY GENERATED BY DEFAULT (this value is retrieved in case of id columns)
        column_default_value = nil if (column_default_value && column_default_value.upcase =~ /IDENTITY GENERATED BY DEFAULT/i)
        # 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|bigint/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_stmt(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 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 1182

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_database(dbName, codeSet = nil, mode = nil) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1434

def create_database(dbName, codeSet=nil, mode=nil)
  connect_str = build_conn_str_for_dbops()

  #Ensure connection is closed before trying to drop a database.
  #As a connect call would have been made by call seeing connection in active
  disconnect!

  begin
    createConn = IBM_DB.connect(connect_str, '', '')
  rescue StandardError => connect_err
    raise "Failed to connect to server due to: #{connect_err}"
  end

  if(IBM_DB.createDB(createConn,dbName,codeSet,mode))
    IBM_DB.close(createConn)
    return true
  else
    error = IBM_DB.getErrormsg(createConn, IBM_DB::DB_CONN)
    IBM_DB.close(createConn)
    raise "Could not create Database due to: #{error}"
  end
end

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

DATABASE STATEMENTS



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 714

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 1241

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 701

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
  return nil if @connection.nil? || @connection == false
  IBM_DB.close(@connection) rescue nil
end

#distinct(columns, order_by) ⇒ Object

Add distinct clause to the sql if there is no order by specified



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1823

def distinct(columns, order_by)
  if order_by.nil?
    "DISTINCT #{columns}"
  else
    "#{columns}"
  end
end

#drop_database(dbName) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1411

def drop_database(dbName)
  connect_str = build_conn_str_for_dbops()

  #Ensure connection is closed before trying to drop a database. 
  #As a connect call would have been made by call seeing connection in active
  disconnect!

  begin
    dropConn = IBM_DB.connect(connect_str, '', '')
  rescue StandardError => connect_err
    raise "Failed to connect to server due to: #{connect_err}"
  end

  if(IBM_DB.dropDB(dropConn,dbName))
    IBM_DB.close(dropConn)
    return true
  else
    error = IBM_DB.getErrormsg(dropConn, IBM_DB::DB_CONN)
    IBM_DB.close(dropConn)
    raise "Could not drop Database due to: #{error}"
  end
end

#exec_query(sql, name = 'SQL', binds = []) ⇒ Object

Executes sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1065

def exec_query(sql, name = 'SQL', binds = [])
  begin
    param_array = binds.map do |column,value|
      quote_value_for_pstmt(value, column)
    end

    stmt = prepare(sql, name)

     if( stmt )
       if(execute_prepared_stmt(stmt, param_array))
         return stmt
       end
     else
       return false
     end
  ensure
    @offset = @limit = nil
  end
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 1087

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

#execute_prepared_stmt(pstmt, param_array = nil) ⇒ Object

Praveen Executes the prepared statement ReturnsTrue on success and False on Failure



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1043

def execute_prepared_stmt(pstmt, param_array = nil)
  if !param_array.nil? && param_array.size < 1
    param_array = nil
  end

  if( !IBM_DB.execute(pstmt, param_array) )
    error_msg = IBM_DB.getErrormsg(pstmt, IBM_DB::DB_STMT)
    if !error_msg.empty?
      error_msg = "Statement execution failed: " + error_msg
    else
      error_msg = "Statement execution failed"
    end
    IBM_DB.free_stmt(pstmt) if pstmt
    raise StatementInvalid, error_msg
  else
    return true
  end
end

#fetch_data(stmt) ⇒ Object

Calls the servertype select method to fetch the data



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 800

def fetch_data(stmt)
  if(stmt)
    begin
      return @servertype.select(stmt)
    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_stmt(stmt) if stmt
    end
  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 1559

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_stmt(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_stmt(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(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = []) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 984

def insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [] )
  sql, binds = [to_sql(arel),binds]

  #unless IBM_DBAdapter.respond_to?(:exec_insert)
  if binds.nil? || binds.empty?
    return insert_direct(sql, name, pk, id_value, sequence_name)
  end

  clear_query_cache if defined? clear_query_cache
  if stmt = exec_insert(sql, name, binds)
    begin
      @sql << sql
      return id_value || @servertype.last_generated_id(stmt)
    ensure
      IBM_DB.free_stmt(stmt) if stmt
    end
  end
end

#insert_direct(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 965

def insert_direct(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_stmt(stmt) if 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 899

def insert_fixture(fixture, table_name)
  if(fixture.respond_to?(:keys))
    insert_query = "INSERT INTO #{quote_table_name(table_name)} ( #{fixture.keys.join(', ')})"
  else
    insert_query = "INSERT INTO #{quote_table_name(table_name)} ( #{fixture.key_list})"
  end

  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 )
      IBM_DB.free_stmt(stmt) if stmt
      raise "Failed to insert due to: #{error_msg}"
    else
      IBM_DB.free_stmt(stmt) if 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 640

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 1370

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"},
    :graphic     => { :name => "graphic", :limit => 1},
    :vargraphic  => { :name => "vargraphic", :limit => 1},
    :bigint      => { :name => "bigint"}
  }
end

#prepare(sql, name = nil) ⇒ Object

Praveen Prepares 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 1032

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

#prepared_insert(pstmt, param_array = nil, id_value = nil) ⇒ Object

Praveen Performs an insert using the prepared statement 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 1007

def prepared_insert(pstmt, param_array = nil, id_value = nil)
  if @handle_lobs_triggered  #Ensure the array of sql is cleared if they have been handled in the callback
    @sql                   = []
    @sql_parameter_values  = []
    @handle_lobs_triggered = false
  end

  clear_query_cache if defined? clear_query_cache

  begin
    if execute_prepared_stmt(pstmt, param_array)
      @sql << @prepared_sql
      @sql_parameter_values << param_array
      return id_value || @servertype.last_generated_id(pstmt)
    end
  rescue StandardError => insert_err
    raise insert_err
  ensure
    IBM_DB.free_stmt(pstmt) if pstmt
  end
end

#prepared_select(sql_param_hash, 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 736

def prepared_select(sql_param_hash, name = nil)
  # Replaces {"= NULL" with " IS NULL"} OR {"IN (NULL)" with " IS NULL"}

  results = []
  # Invokes the method +prepare+ in order prepare the SQL
  # IBM_DB.Statement is returned from which the statement is executed and results fetched
  pstmt = prepare(sql_param_hash["sqlSegment"], name)
  if(execute_prepared_stmt(pstmt, sql_param_hash["paramArray"]))
    begin
      results = @servertype.select(pstmt)
    rescue StandardError => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(pstmt, 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_stmt(pstmt) if pstmt
    end
  end
  # The array of record hashes is returned
  results
end

#prepared_select_values(sql_param_hash, 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 767

def prepared_select_values(sql_param_hash, name = nil)
  # Replaces {"= NULL" with " IS NULL"} OR {"IN (NULL)" with " IS NULL"}
  results = []
  # Invokes the method +prepare+ in order prepare the SQL
  # IBM_DB.Statement is returned from which the statement is executed and results fetched
  pstmt = prepare(sql_param_hash["sqlSegment"], name)
  if(execute_prepared_stmt(pstmt, sql_param_hash["paramArray"]))
    begin
      results = @servertype.select_rows(sql_param_hash["sqlSegment"], name, pstmt, results)
      if results
        return results.map { |v| v[0] }
      else
        nil
      end
    rescue StandardError => fetch_error # Handle driver fetch errors
      error_msg = IBM_DB.getErrormsg(pstmt, 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_stmt(pstmt) if pstmt
    end
  end
  # The array of record hashes is returned
  results
end

#prepared_update(pstmt, param_array = nil) ⇒ Object Also known as: prepared_delete

Praveen



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1116

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

  clear_query_cache if defined? clear_query_cache

  begin
    if execute_prepared_stmt(pstmt, param_array)
      @sql << @prepared_sql
      @sql_parameter_values << param_array
      # Retrieves the number of affected rows
      IBM_DB.num_rows(pstmt)
      # Ensures to free the resources associated with the statement
		  end
  rescue StandardError => updt_err
    raise updt_err
  ensure
    IBM_DB.free_stmt(pstmt) if pstmt
  end
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 1525

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_stmt(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 1282

def quote(value, column = nil)
  return value.quoted_id if value.respond_to?(:quoted_id)

  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 && !(column.sql_type =~ /for bit data/i)
      # 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
          super 
        else
          "#{value}"
        end 
    end
    when TrueClass then quoted_true    # return '1' for true
    when FalseClass then quoted_false  # return '0' for false
    when nil        then "NULL"
    when Date, Time then "'#{quoted_date(value)}'"
    when Symbol     then "'#{quote_string(value.to_s)}'"
    else
      unless caller[0] =~ /insert_fixture/i 
        "'#{quote_string(YAML.dump(value))}'"
      else
        "#{quote_string(YAML.dump(value))}"
      end
  end
end

#quote_column_name(name) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1360

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 1345

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

#quote_value_for_pstmt(value, column = nil) ⇒ Object

Praveen



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1251

def quote_value_for_pstmt(value, column=nil)

  return value.quoted_id if value.respond_to?(:quoted_id)

  case value
    when String, ActiveSupport::Multibyte::Chars then
      value = value.to_s
      if column && [:integer, :float].include?(column.type)
        value = column.type == :integer ? value.to_i : value.to_f
        value
      else
        value
      end
    when NilClass                 then nil
    when TrueClass                then 1
    when FalseClass               then 0
    when Float, Fixnum, Bignum    then value
    # BigDecimals need to be output in a non-normalized form and quoted.
    when BigDecimal               then value.to_s('F')
    when Numeric, Symbol          then value.to_s
    else
      if value.acts_like?(:date) || value.acts_like?(:time)
        quoted_date(value)
      else
        value.to_yaml
      end
  end
end

#quoted_false ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1356

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 1352

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 695

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 1783

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 1860

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 1776

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 1764

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_stmt(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 1191

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, binds = []) ⇒ 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
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)

  results = fetch_data(stmt)
  # The array of record hashes is returned
  results
end



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 837

def select(sql, name = nil, binds = [])
  # Replaces {"= NULL" with " IS NULL"} OR {"IN (NULL)" with " IS NULL"}
  sql.gsub!( /(=\s*NULL|IN\s*\(NULL\))/i, " IS NULL" )

  results = []

  if(binds.nil? || binds.empty?)
    stmt = execute(sql, name)
  else
    stmt = exec_query(sql, name, binds)
  end

  if( stmt ) 
    results = fetch_data(stmt)
  end

  return 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 890

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 859

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
      results = @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_stmt(stmt) if 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 636

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 629

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 1480

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 1485

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_stmt(stmt)  if 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

#to_sql(arel) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 615

def to_sql(arel)
  if arel.respond_to?(:ast)
    visitor.accept(arel.ast)
  else
    arel
  end

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, graphic, vargraphic data types.



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1459

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(arel, name = nil, binds = []) ⇒ Object Also known as: delete 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1144

def update(arel, name = nil, binds = [])
  sql = to_sql(arel)

  # 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

  clear_query_cache if defined? clear_query_cache

  if binds.nil? || binds.empty?
    update_direct(sql, name)
  else
    if stmt = exec_query(sql,name,binds)
      IBM_DB.num_rows(stmt)
    end
  end
end

#update_direct(sql, name = nil) ⇒ Object

Executes an “UPDATE” SQL statement



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1096

def update_direct(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

  # 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_stmt(stmt) if stmt
    end
  end
end