/**
	 * Constructor
	 *
	 *	@param string      $table  name of the table in the db schema relating to child class
	 *	@param string      $key    name of the primary key field in the table
	 *	@param CBdatabase  $db     CB Database object
	 */
	public function __construct( $table, $key, &$db = null ) {
		parent::__construct( $table, $key, $db );
	}