拆解跨天时间(mysql游标循环)

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本文链接： https://blog.csdn.net/liminghui4321/article/details/102763052

原始题目需求

**原始表,**需要求出每个品牌的促销天数

结果表

思路:①先将跨天日期拆解为以天为单位的记录
②聚合count(distinct tdate)

1.原表建表和插入数据sql脚本

/*
 Navicat Premium Data Transfer

 Source Server         : windows1
 Source Server Type    : MySQL
 Source Server Version : 50527
 Source Host           : localhost:3306
 Source Schema         : sqltest

 Target Server Type    : MySQL
 Target Server Version : 50527
 File Encoding         : 65001

 Date: 26/10/2019 20:45:40
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for sales
-- ----------------------------
DROP TABLE IF EXISTS `sales`;
CREATE TABLE `sales`  (
  `id` int(11) NOT NULL,
  `brand` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `startdate` date NULL DEFAULT NULL,
  `enddate` date NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Records of sales
-- ----------------------------
INSERT INTO `sales` VALUES (1, 'nike', '2018-09-01', '2018-09-05');
INSERT INTO `sales` VALUES (2, 'nike', '2018-09-03', '2018-09-06');
INSERT INTO `sales` VALUES (3, 'nike', '2018-09-09', '2018-09-15');
INSERT INTO `sales` VALUES (4, 'oppo', '2018-08-04', '2018-08-05');
INSERT INTO `sales` VALUES (5, 'oppo', '2018-08-04', '2018-08-15');
INSERT INTO `sales` VALUES (6, 'vivo', '2018-08-15', '2018-08-21');
INSERT INTO `sales` VALUES (7, 'vivo', '2018-09-02', '2018-09-12');

SET FOREIGN_KEY_CHECKS = 1;

2.结果表建表sql脚本

/*
 Navicat Premium Data Transfer

 Source Server         : windows1
 Source Server Type    : MySQL
 Source Server Version : 50527
 Source Host           : localhost:3306
 Source Schema         : sqltest

 Target Server Type    : MySQL
 Target Server Version : 50527
 File Encoding         : 65001

 Date: 26/10/2019 20:46:39
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for sales2
-- ----------------------------
DROP TABLE IF EXISTS `sales2`;
CREATE TABLE `sales2`  (
  `id` int(11) NULL DEFAULT NULL,
  `brand` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `tdate` date NULL DEFAULT NULL
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

SET FOREIGN_KEY_CHECKS = 1;

3.游标实现代码

drop PROCEDURE if EXISTS p3;
create procedure p3()
begin
    declare id ,gt,it int;
    declare brand varchar(15);
	declare sdate,edate,mdate date;
    declare flag int default 0;
    -- 声明游标
    declare cur cursor for select *,datediff(enddate,startdate) from sales;
    declare continue handler for not found set flag = 1;
    -- 打开游标
    open cur;
    -- 获取结果
    l2:loop 

   fetch cur into id,brand,sdate,edate,gt;
    if flag=1 then -- 当无法fetch会触发handler continue
        leave l2;
    end if;
    -- 逻辑处理,拆解跨天
    IF(gt>=0) THEN 
        set it=0;
        while it<=gt DO 
            insert into sales2 values(id, brand,date_add(sdate,interval it day));
            set it=it+1;
        end while;
    end if; 
    -- 关闭游标
    end loop;
    close cur; 
		
end;

call p3();-- 不报错

4.查询结果表

select * from sales2;

5.最终需求结果

select brand,count(distinct tdate) as all_days from sales2 GROUP BY brand;