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, #limit_not_supported_types, #prepare, #remove_column, #select, #select_rows, #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 3123

def change_column(table_name, column_name, type, options)
  if !options[:null].nil? && !options[:null]
    execute "ALTER TABLE #{table_name} MODIFY #{column_name} #{@adapter.type_to_sql(type, options[:limit], options[:precision], options[:scale])} NOT NULL"
  else
    execute "ALTER TABLE #{table_name} MODIFY #{column_name} #{@adapter.type_to_sql(type, options[:limit], options[:precision], options[:scale])}"  
  end 
  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 3138

def change_column_default(table_name, column_name, default)
  sql_type = nil
  is_nullable = true
  @adapter.columns(table_name).select do |col| 
     if (col.name == column_name)
			  sql_type =  @adapter.type_to_sql(col.sql_type, col.limit, col.precision, col.scale)
        is_nullable = col.null 
     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)}"
  change_column_sql << " NOT NULL" unless is_nullable 
  stmt = execute(change_column_sql)
  reorg_table(table_name)
  # Ensures to free the resources associated with the statement
  ensure
    IBM_DB.free_stmt(stmt) if stmt
end

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

IDS specific ALTER TABLE statement to change the nullability of a column



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 3158

def change_column_null(table_name,column_name,null,default)
  if !default.nil?
    change_column_default table_name, column_name, default
  end
  sql_type = nil
  @adapter.columns(table_name).select do |col| 
    if (col.name == column_name)
			sql_type =  @adapter.type_to_sql(col.sql_type, col.limit, col.precision, col.scale)
    end
  end
  if !null.nil?
    if !null
      change_column_sql = "ALTER TABLE #{table_name} MODIFY #{column_name} #{sql_type} NOT NULL"
    else
      change_column_sql = "ALTER TABLE #{table_name} MODIFY #{column_name} #{sql_type}"     
    end
    stmt = execute(change_column_sql)
    reorg_table(table_name)
  end

  ensure
    IBM_DB.free_stmt(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 3189

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

#get_double_mapping ⇒ Object

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



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 3200

def get_double_mapping
  return "double precision"
end

#get_limit_offset_clauses(limit, offset) ⇒ Object 



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 3204

def get_limit_offset_clauses(limit, offset)
  retHash = {"startSegment" => "", "endSegment" => ""}
  if limit != 0
    if !offset.nil?
      # Modifying the SQL to utilize the skip and limit amounts
      retHash["startSegment"] = " SELECT SKIP #{offset} LIMIT #{limit} "
    else
      # Modifying the SQL to retrieve only the first #{limit} rows
      retHash["startSegment"] = " SELECT FIRST #{limit} "
    end
  else
    retHash["startSegment"] = " SELECT * FROM (SELECT "
    retHash["endSegment"] = " ) WHERE 0 = 1 "
  end
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 3195

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 3260

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

#primary_key_definition(start_id) ⇒ Object

End of rename_column



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 3119

def primary_key_definition(start_id)
  return "SERIAL(#{start_id}) 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 3221

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

#query_offset_limit!(sql, offset, limit, options) ⇒ Object

Handling offset/limit as per Informix requirements



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 3238

def query_offset_limit!(sql, offset, limit, options)
  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

IDS specific ALTER TABLE statement to rename a column



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 3085

def rename_column(table_name, column_name, new_column_name)
  _table_name      = table_name.to_s
  _column_name     = column_name.to_s
  _new_column_name = new_column_name.to_s

  nil_condition    = _table_name.nil? || _column_name.nil? || _new_column_name.nil?
  empty_condition  = _table_name.empty? || 
                       _column_name.empty? || 
                         _new_column_name.empty? unless nil_condition

  if nil_condition || empty_condition
    raise ArgumentError,"One of the arguments passed to rename_column is empty or nil"
  end

  begin
    rename_column_sql = "RENAME COLUMN #{table_name}.#{column_name} TO \
         #{new_column_name}"

    unless stmt = execute(rename_column_sql)
      error_msg = IBM_DB.getErrormsg(@adapter.connection, IBM_DB::DB_CONN )
      if error_msg && !error_msg.empty?
        raise "Rename column failed : #{error_msg}"
      else
        raise StandardError.new('An unexpected error occurred during renaming the column')
      end
    end

    reorg_table(_table_name)

  ensure
    IBM_DB.free_stmt(stmt) if stmt
  end #End of begin
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 3183

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 3267

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 3276

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 3291

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 3081

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 3283

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