mysql番号生成

1、シリアル番号の生成方法

DELIMITER $$
CREATE DEFINER=`root`@`localhost` FUNCTION `get_workNo`() RETURNS varchar(45) CHARSET utf8
BEGIN
DECLARE newWorkNo varCHAR (45) ;
	DECLARE currentDate varCHAR (15) ;--     ,             
	DECLARE maxNo INT DEFAULT 0 ;
	DECLARE oldWorkNo VARCHAR (25) DEFAULT '' ;--                     
	
	
	SELECT SUBSTRING(DATE_FORMAT(NOW(), '%Y%m'),3,6) INTO currentDate ;
	
	SELECT IFNULL(workNo, '') INTO oldWorkNo     
	  FROM operation_work     
	  WHERE SUBSTRING(workNo, 3, 4) = currentDate          
	ORDER BY id DESC LIMIT 1 ; --                     
	
	IF oldWorkNo != '' THEN     
		SET maxNo = CONVERT(SUBSTRING(oldWorkNo, -4), DECIMAL) ;-- SUBSTRING(oldOrderNo, -5)：        ‘‘       5      
	END IF ;
	
	SELECT     
		CONCAT('TS', currentDate,  LPAD((maxNo + 1), 4, '0')) INTO newWorkNo ;
	
RETURN newWorkNo;
END$$
DELIMITER ;

2、データ挿入時のトリガー

USE `it_system`;
DELIMITER $$
CREATE DEFINER=`root`@`localhost` TRIGGER `operation_work_BINS` BEFORE INSERT ON `operation_work` FOR EACH ROW
begin SET @workNo = get_workNo();    
       set NEW.workNo=@workNo;
end