protected static function is_numeric( $type ) {
		switch ( $type ) {
			case self::INT:
			case self::TINYINT:
			case self::MEDIUMINT:
			case self::BIGINT:
			case self::DOUBLE:
			case self::FLOAT:
			case self::REAL:
			case self::DECIMAL:
				return true;
				break;
			default:
				return false;
				break;
		}
	}