数据库 UPDATE多条记录不一样值，同时UPDATE多个字段

时间 2019-11-06

标签数据库 update 多条记录不一样同时多个字段栏目 SQL 繁體版

原文原文链接

需求sql

以下两张表student（学生表）、score（测试成绩表）app

现须要统计：2015-03-10日以后，性别 age=1 的测试成绩的总分与平均分。oop

要求：使用一个SQL统计score表，将结果更新到student表的score_sum和score_avg字段中。性能

结果如图：测试

实现：spa

若是咱们只须要更新一个字段，MYSQL和ORACLE语法是同样的，在 set 后面跟一个子查询便可，以下：.net

UPDATE student D
   SET D.score_sum =
       (
         SELECT
                SUM(B.score)
           FROM score B
          WHERE B.studentId = D.id
            AND b.examTime >= '2015-03-10'
          GROUP BY B.studentId
       )
WHERE D.id =
       (
         SELECT
       E.id FROM
       (
                  SELECT
                DISTINCT a.studentId AS id
                    FROM score A
                   WHERE A.examTime >= '2015-03-10'
                ) E
          WHERE E.id = D.id
       )
   AND d.age = 1;blog

如今咱们须要同时更新2个字段，最不通过大脑思考的方法就是 “为每一个 set 后面都跟一个子查询”，ip

假如咱们要 set 十个字段或者更多字段呢？很显然，这样在性能上是很不合适的方法。get

同时更新多个字段在MYSQL和ORACLE中的方法是不同，MYSQL须要链接表，ORACLE使用 set(...) 便可

（看了下面的SQL你会发现，仍是ORACLE简单易用、易懂）

1) MYSQL 实现咱们最终的需求，语句以下：

UPDATE student D
LEFT JOIN (SELECT
       B.studentId,
                SUM(B.score) AS s_sum,
                ROUND(AVG(B.score),1) AS s_avg
           FROM score B
          WHERE b.examTime >= '2015-03-10'
          GROUP BY B.studentId) C
    ON (C.studentId = D.id)

   SET D.score_sum = c.s_sum,
       D.score_avg = c.s_avg
WHERE D.id =
       (
         SELECT
       E.id FROM
       (
                  SELECT
                DISTINCT a.studentId AS id
                    FROM score A
                   WHERE A.examTime >= '2015-03-10'
                ) E
          WHERE E.id = D.id
       )
   AND d.age = 1;

2) ORACLE 实现咱们最终的需求，语句以下：

UPDATE student D
SET (D.score_sum, D.score_avg) = (
         SELECT
                SUM(B.score) AS s_sum,
                ROUND(AVG(B.score),1) AS s_avg
           FROM score B
          WHERE b.examTime >= '2015-03-10'
            AND B.studentId = D.id
          GROUP BY B.studentId
)
WHERE D.id =
       (
         SELECT
       E.id FROM
       (
                  SELECT
                DISTINCT a.studentId AS id
                    FROM score A
                   WHERE A.examTime >= '2015-03-10'
                ) E
          WHERE E.id = D.id
       )
   AND d.age = 1;

本文中用到的2个知识点：

一、更新多条记录，每条记录不一样值。

二、同时更新多个字段的方法。

===== 将 age = 1 而且没有测试成绩的同窗给予默认值0，调整SQL以下 =====

UPDATE student D
LEFT JOIN (SELECT
       B.studentId,
                SUM(B.score) AS s_sum,
                ROUND(AVG(B.score),1) AS s_avg
           FROM score B
          WHERE b.examTime >= '2015-03-10'
          GROUP BY B.studentId) C
    ON (C.studentId = D.id)

   SET D.score_sum = IFNULL(c.s_sum,0),
       D.score_avg = IFNULL(c.s_avg,0)

WHERE D.id =
       (
         SELECT
       E.id FROM
       (
                  SELECT
                DISTINCT a.studentId AS id
                    FROM score A
                   ##WHERE A.examTime >= '2015-03-10'
                ) E
          WHERE E.id = D.id
       )

AND d.age = 1;

结果以下：

Test SQL

[sql] view plain copy

/*
SQLyog Ultimate v10.00 Beta1
MySQL - 5.5.28 : Database - test
*********************************************************************
*/
/*!40101 SET NAMES utf8 */;
/*!40101 SET SQL_MODE=''*/;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
CREATE DATABASE /*!32312 IF NOT EXISTS*/`test` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `test`;
/*Table structure for table `score` */
DROP TABLE IF EXISTS `score`;
CREATE TABLE `score` (
`id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
`studentId` int(11) DEFAULT NULL COMMENT '学员ID',
`subjectName` varchar(20) DEFAULT NULL COMMENT '科目名称',
`score` float DEFAULT NULL COMMENT '考试成绩',
`examTime` datetime DEFAULT NULL COMMENT '考试时间',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=25 DEFAULT CHARSET=utf8;
/*Data for the table `score` */
insert into `score`(`id`,`studentId`,`subjectName`,`score`,`examTime`) values (1,1,'语文',70,'2015-02-26 18:11:39'),(2,1,'数学',80,'2015-03-26 18:11:50'),(3,1,'英语',76,'2015-04-26 18:11:56'),(4,1,'历史',96,'2015-05-26 18:12:02'),(5,2,'语文\r\n数学\r\n英语\r\n历史\r\n语文',84,'2015-02-26 18:11:39'),(6,2,'数学',56,'2015-03-26 18:11:50'),(7,2,'英语',86,'2015-04-26 18:11:56'),(8,2,'历史',45,'2015-05-26 18:12:02'),(9,3,'语文',87,'2015-02-26 18:11:39'),(10,3,'数学',98,'2015-03-26 18:11:50'),(11,3,'英语',67,'2015-04-26 18:11:56'),(12,3,'历史',86,'2015-05-26 18:12:02'),(13,4,'语文',97,'2015-02-26 18:11:39'),(14,4,'数学',68,'2015-03-26 18:11:50'),(15,4,'英语',79,'2015-04-26 18:11:56'),(16,4,'历史',83,'2015-05-26 18:12:02'),(17,5,'语文',92,'2015-02-26 18:11:39'),(18,5,'数学',93,'2015-03-26 18:11:50'),(19,5,'英语',65,'2015-04-26 18:11:56'),(20,5,'历史',88,'2015-05-26 18:12:02'),(21,6,'语文',87,'2015-01-05 18:48:48'),(22,6,'数学',67,'2015-01-05 18:48:48'),(23,6,'英语',99,'2015-01-05 18:48:48'),(24,6,'历史',88,'2015-01-05 18:48:48');
/*Table structure for table `student` */
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
`id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
`name` varchar(20) DEFAULT NULL COMMENT '姓名',
`score_sum` varchar(20) DEFAULT NULL COMMENT '总成绩',
`score_avg` varchar(20) DEFAULT NULL COMMENT '平均成绩',
`age` int(11) DEFAULT NULL COMMENT '1男0女',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;
/*Data for the table `student` */
insert into `student`(`id`,`name`,`score_sum`,`score_avg`,`age`) values (1,'小明','252','84',1),(2,'小王','187','62.3',1),(3,'莉莉','','',0),(4,'柱子','230','76.7',1),(5,'大毛','','',0),(6,'亮子','0','0',1);
/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;