public function addColumn( $type, $column, $field ) {
		$table = $type;
		$type = $field;
		$table = $this->safeTable($table);
		$column = $this->safeColumn($column);
		$type = array_key_exists($type, $this->typeno_sqltype) ? $this->typeno_sqltype[$type] : '';
		$sql = "ALTER TABLE $table ADD COLUMN $column $type ";
		$this->adapter->exec( $sql );
	}