MySQL使用过程存储生成唯一订单号

/*
Navicat MySQL Data Transfer

Source Server         : local
Source Server Version : 50640
Source Host           : localhost:3306
Source Database       : springsecurity

Target Server Type    : MYSQL
Target Server Version : 50640
File Encoding         : 65001

Date: 2018-08-25 22:10:57
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for orders
-- ----------------------------
DROP TABLE IF EXISTS `orders`;
CREATE TABLE `orders` (
  `orderNo` varchar(30) NOT NULL COMMENT ‘订单号‘,
  `productTypes` varchar(11) NOT NULL COMMENT ‘商品类型‘,
  `orderNumber` int(11) DEFAULT NULL COMMENT ‘商品数量‘,
  `unitPrice` decimal(10,2) unsigned zerofill DEFAULT NULL COMMENT ‘单价‘,
  `totalPrice` decimal(10,2) unsigned zerofill DEFAULT NULL COMMENT ‘总价‘,
  PRIMARY KEY (`orderNo`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT;

CREATE PROCEDURE `generate`(in orderNamePre char(2),in productTypes VARCHAR(20),
in orderNumber INT(10),in unitPrice decimal(10,2))  
-- 输入当前订单名以及时间长度，输出订单号
BEGIN  
  DECLARE newOrderNo varchar(25);
  DECLARE currentDate varCHAR (15) ;-- 当前日期,有可能包含时分秒   
  DECLARE maxNo INT DEFAULT 0 ; -- 离现在最近的满足条件的订单编号的流水号最后5位，如：SH2013011000002的maxNo=2    
  DECLARE oldOrderNo VARCHAR (25) DEFAULT ‘‘ ;-- 离现在最近的满足条件的订单编号   
    
--   SELECT DATE_FORMAT(NOW(), ‘%Y%m%d%H%i%s‘) INTO currentDate ;-- 年月日时分秒共14位数
    SELECT DATE_FORMAT(NOW(), ‘%Y%m%d%H%i‘) INTO currentDate ;-- 年月日时分秒共14位数
    
        -- SUBSTRING() 字符串截取函数
  SELECT IFNULL(orderNo, ‘‘) INTO oldOrderNo   
  FROM orders
  WHERE SUBSTRING(orderNo, 3, 12) = currentDate   -- 截取时间段
    AND SUBSTRING(orderNo, 1, 2) = orderNamePre    -- 截取当前订单名
  ORDER BY orderNo DESC LIMIT 1 ; -- 有多条时只显示离现在最近的一条   
    
    -- 判断是否拥有当前时间段订单
  IF oldOrderNo != ‘‘ THEN   
    SET maxNo = SUBSTRING(oldOrderNo, -5);
  END IF ;  
    
  SELECT CONCAT(orderNamePre, currentDate,  LPAD((maxNo + 1), 5, ‘0‘)) INTO newOrderNo ;
        -- LPAD((maxNo + 1), 5, ‘0‘)：如果不足5位，将用0填充左边   
  INSERT INTO orders (orderNo,productTypes,orderNumber,unitPrice,totalPrice) VALUES (newOrderNo,productTypes,orderNumber,unitPrice,FORMAT(orderNumber*unitPrice,2)) ; -- 向订单表中插入数据   
END

CALL generate("TT","休闲裤",2,198.60)