MySQL入门篇之高级查询
Posted 小王Java
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前言
好久不见，今日为大家带来mysql中的查询，
查询及其重要，敲重点了，下面进入具体教程
准备前提
新建数据表
t_student:学生表
t_teacher:教师表 score:成绩表 course:课程表 各个表之间都有关联 课程表关联教师表：c_id：课程编号 t_id：教师编号 c_name：课程名称 成绩表关联学生表与课程表：s_id：学生id，c_id：课程id score:课程成绩
/*
SQLyog Ultimate v12.09 (64 bit)
MySQL - 5.7.24 : Database - demo
*********************************************************************
*/
/*!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*/`demo` /*!40100 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci */;
USE `demo`;
/*Table structure for table `course` */
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
`c_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`c_name` varchar(32) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`t_id` int(11) DEFAULT NULL,
PRIMARY KEY (`c_id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
/*Data for the table `course` */
insert into `course`(`c_id`,`c_name`,`t_id`) values (1,语文,1),(2,数学,3),(3,英语,2);
/*Table structure for table `score` */
DROP TABLE IF EXISTS `score`;
CREATE TABLE `score` (
`s_id` int(10) NOT NULL,
`c_id` int(11) DEFAULT NULL,
`score` decimal(10,2) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
/*Data for the table `score` */
insert into `score`(`s_id`,`c_id`,`score`) values (1,2,90.00),(1,1,87.00),(1,3,68.50),(3,1,79.00),(3,2,89.00),(3,3,99.00),(2,3,86.00),(2,1,79.00),(2,2,87.00);
/*Table structure for table `t_student` */
DROP TABLE IF EXISTS `t_student`;
CREATE TABLE `t_student` (
`s_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`s_name` varchar(32) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`s_birthday` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`s_sex` char(12) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
PRIMARY KEY (`s_id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
/*Data for the table `t_student` */
insert into `t_student`(`s_id`,`s_name`,`s_birthday`,`s_sex`) values (1,张旺,2021-07-25 16:09:46,男),(2,李四,2021-07-25 16:09:42,女),(3,张无忌,2021-07-25 16:10:14,男);
/*Table structure for table `t_teacher` */
DROP TABLE IF EXISTS `t_teacher`;
CREATE TABLE `t_teacher` (
`t_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`t_name` varchar(32) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`c_id` int(11) DEFAULT NULL,
PRIMARY KEY (`t_id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
/*Data for the table `t_teacher` */
insert into `t_teacher`(`t_id`,`t_name`,`c_id`) values (1,张三,1),(2,李四,3),(sql server查询问题。