通过存储过程解决并发生成唯一订单号

DELIMITER $$
 
USE `roamerbuddy`$$
 
DROP PROCEDURE IF EXISTS `generate_orderNo`$$
 
CREATE DEFINER=`root`@`%` PROCEDURE `generate_orderNo`(
  IN orderNamePre CHAR(4),
  IN num INT,
  OUT newOrderNo VARCHAR (25)
)
BEGIN
  -- 订单变化的值
  DECLARE orderNameValue INT ;
  -- 更新行数
  DECLARE updateRow INT ;
  -- 当前日期,有可能包含时分秒  
  DECLARE currentTime DATETIME ;
  -- 订单号   
  DECLARE orderCode VARCHAR (64) ;
  -- 异常处理
  DECLARE CONTINUE HANDLER FOR 1062
  SET currentTime = NOW() ;
  
  SELECT 
    IFNULL(gs.ordervalue, 0) INTO orderNameValue 
  FROM
    generate_serialno gs 
  WHERE id = 1 ;
  
  SET currentTime = NOW() ;
 
  -- 打开自动提交
  SET autocommit = 1 ;
  IF TRUE 
  THEN 
  INSERT INTO generate_serialno (id, ordervalue, ordertime) 
  VALUES
    (1, 1, currentTime) ;
  END IF ;
  UPDATE 
    generate_serialno obj 
  SET
    obj.ordervalue = 
    CASE
      WHEN TO_DAYS(currentTime) > TO_DAYS(obj.ordertime) 
      THEN 1 
      ELSE orderNameValue + 1 
    END,
    obj.ordertime = currentTime 
  WHERE (
      obj.id = 1 
      AND obj.ordervalue = orderNameValue
    ) ;
  SET updateRow = ROW_COUNT() ;
  WHILE
    ! updateRow = 1 DO -- 获得当前的订单和变化的值   
    SELECT 
      IFNULL(gs.ordervalue, 0) INTO orderNameValue 
    FROM
      generate_serialno gs 
    WHERE id = 1 ;
    UPDATE 
      generate_serialno obj 
    SET
      obj.ordervalue = 
      CASE
        WHEN TO_DAYS(currentTime) > TO_DAYS(obj.ordertime) 
        THEN 1 
        ELSE orderNameValue + 1 
      END,
      obj.ordertime = currentTime 
    WHERE (
        obj.id = 1 
        AND obj.ordervalue = orderNameValue
      ) ;
    SET updateRow = ROW_COUNT() ;
  END WHILE ;
  IF num = 8 
  THEN -- 根据年月日生成订单编号,订单编号形式:前缀+年月日+流水号，如：SH2013011000002     
  SELECT 
    CONCAT(
      orderNamePre,
      DATE_FORMAT(currentTime, '%Y%m%d'),
      LPAD(orderNameValue, num, '0')
    ) INTO orderCode ;
  ELSEIF num = 14 
  THEN -- 根据年月日时分秒生成订单编号,订单编号形式：前缀+年月日时分秒+流水号，如：SH2013011010050700001,个人不推荐使用这种方法生成流水号     
  SELECT 
    CONCAT(
      orderNamePre,
      DATE_FORMAT(currentTime, '%Y%m%d%H%i%s'),
      LPAD(orderNameValue, num, '0')
    ) INTO orderCode ;
  ELSE -- 根据年月日时分生成订单编号,订单形式：前缀+年月日时分+流水号,如：SH20130110100900005
  SELECT 
    CONCAT(
      orderNamePre,
      DATE_FORMAT(currentTime, '%Y%m%d%H%i'),
      LPAD(orderNameValue, num, '0')
    ) INTO orderCode ;
  END IF ;
  SELECT 
    orderCode ;
END$$
 
DELIMITER ;

DROP TABLE IF EXISTS `generate_serialno`;
 
CREATE TABLE `generate_serialno` (
  `id` int(20) DEFAULT NULL,
  `orderno` varchar(50) DEFAULT NULL,
  `orderpre` varchar(30) DEFAULT NULL,
  `ordervalue` int(20) DEFAULT NULL,
  `ordertime` datetime DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
insert into `generate_serialno` (`id`, `ordervalue`) values('1','1');