Class: ActiveRecord::ConnectionAdapters::IBM_IDS

Inherits:
IBM_DataServer show all
Defined in:
lib/active_record/connection_adapters/ibm_db_adapter.rb

Overview

class IBM_DB2_I5

Instance Method Summary collapse

Methods inherited from IBM_DataServer

#check_reserved_words, #create_index_after_table, #execute, #initialize, #remove_column, #select_all, #setup_for_lob_table

Constructor Details

This class inherits a constructor from ActiveRecord::ConnectionAdapters::IBM_DataServer

Instance Method Details

#change_column(table_name, column_name, type, options) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1370

def change_column(table_name, column_name, type, options)
  execute "ALTER TABLE #{table_name} MODIFY #{column_name} #{@adapter.type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
  if !options[:default].nil?
     change_column_default(table_name, column_name, options[:default])
  end
  reorg_table(table_name)
end

#change_column_default(table_name, column_name, default) ⇒ Object

IDS specific ALTER TABLE statement to add a default clause IDS requires the data type to be explicitly specified when adding the DEFAULT clause



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1381

def change_column_default(table_name, column_name, default)
  sql_type = nil
  @adapter.columns(table_name).select do |col| 
     if (col.name == column_name)
        sql_type =  @adapter.type_to_sql(col.type, col.limit, col.precision, col.scale)
     end
  end
  # SQL statement which alters column's default value
  change_column_sql = "ALTER TABLE #{table_name} MODIFY #{column_name} #{sql_type} DEFAULT #{@adapter.quote(default)}"
  stmt = execute(change_column_sql)
  # Ensures to free the resources associated with the statement
  ensure
    IBM_DB::free_result stmt if stmt
end

#get_datetime_mapping ⇒ Object

This method returns the IDS SQL type corresponding to the Rails datetime/timestamp type



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1403

def get_datetime_mapping
  return "datetime year to fraction(5)"
end

#get_time_mapping ⇒ Object

This method returns the IDS SQL type corresponding to the Rails time type



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1409

def get_time_mapping
  return "datetime hour to second"
end

#last_generated_id(stmt) ⇒ Object

Method that returns the last automatically generated ID on the given @connection. This method is required by the insert method. IDS returns the last generated serial value in the SQLCA unlike DB2 where the generated value has to be retrieved using the IDENTITY_VAL_LOCAL function. We used the “stmt” parameter to identify the statement resource from which to get the last generated value



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1436

def last_generated_id(stmt)
  IBM_DB::get_last_serial_value(stmt)
end

#primary_key ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1366

def primary_key
  return "SERIAL(100) PRIMARY KEY"
end

#query_offset_limit(sql, offset, limit) ⇒ Object

Handling offset/limit as per Informix requirements



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1414

def query_offset_limit(sql, offset, limit)
  if limit != 0
    if !offset.nil?
      # Modifying the SQL to utilize the skip and limit amounts
      sql.gsub!(/SELECT/i,"SELECT SKIP #{offset} LIMIT #{limit}")
    else
      # Modifying the SQL to retrieve only the first #{limit} rows
      sql = sql.gsub!("SELECT","SELECT FIRST #{limit}")
    end
  else
    # Modifying the SQL to ensure that no rows will be returned
    sql.gsub!(/SELECT/i,"SELECT * FROM (SELECT")
    sql << ") WHERE 0 = 1"
  end
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1362

def rename_column(table_name, column_name, new_column_name)
  execute "RENAME COLUMN #{table_name}.#{column_name} TO #{new_column_name}"
end

#reorg_table(table_name) ⇒ Object

Reorganizes the table for column changes



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1397

def reorg_table(table_name)
  execute("UPDATE STATISTICS FOR TABLE #{table_name}")
end

#set_binary_default(value) ⇒ Object

This method throws an error when trying to create a default value on a BLOB/CLOB column for IDS. The documentation states: “if the column is a BLOB or CLOB datatype, NULL is the only valid default value.”



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1443

def set_binary_default(value)
  unless (value == 'NULL')
    raise "Informix Dynamic Server only allows NULL as a valid default value for a BLOB data type"
  end
end

#set_binary_value ⇒ Object

For Informix Dynamic Server, we treat binary value same as we treat a text value. We support literals by converting the insert into a dummy insert and an update (See handle_lobs method above)



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1452

def set_binary_value
  "'@@@IBMBINARY@@@'"
end

#set_case(value) ⇒ Object

For Informix Dynamic Server, the arguments to the meta-data functions need to be in lower-case



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1467

def set_case(value)
  value.downcase
end

#set_schema(schema) ⇒ Object

IDS does not support the SET SCHEMA syntax



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 1359

def set_schema(schema)
end

#set_text_default(value) ⇒ Object

This method throws an error when trying to create a default value on a BLOB/CLOB column for IDS. The documentation states: “if the column is a BLOB or CLOB datatype, NULL is the only valid default value.”



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

def set_text_default(value)
  unless (value == 'NULL')
    raise "Informix Dynamic Server only allows NULL as a valid default value for a CLOB data type"
  end
end