SQL实战50例:MySQL查询语句练习

一、学生-课程数据库中包括三个表：

1，学生表Student由学号（Sno）、姓名(Sname)、性别(Ssex)、年龄(Sage)、所在系（Sdept）五个属性所组成,可记为

Student(Sno,Sname,Ssex,Sage,Sdept) ，Sno为主码。

课程表Course由课程号（Cno）、课程名、先修课号、学分4个属性组成，可记为：

Course(Cno,Cname,Cpno,Ccredit)，Cno为主码。

学生选课表SC由学号（sno）、课程号(Cno)、成绩(Grade)3个属性组成、可记为

SC(Sno,Cno,Grade) ，其中（Sno,Cno）为主码

下面是创建这三个表及注入数据的SQL：

Student:

/*
Navicat MySQL Data Transfer

Source Server         : aaa
Source Server Version : 80012
Source Host           : localhost:3306
Source Database       : kaoyan

Target Server Type    : MYSQL
Target Server Version : 80012
File Encoding         : 65001

Date: 2020-02-17 12:17:07
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
  `Sno` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `Sname` varchar(15) DEFAULT NULL,
  `Ssex` varchar(5) DEFAULT NULL,
  `Sdept` varchar(6) DEFAULT NULL,
  `Sage` int(11) DEFAULT NULL,
  PRIMARY KEY (`Sno`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

-- ----------------------------
-- Records of student
-- ----------------------------
INSERT INTO `student` VALUES ('1', 'hxz', '男', '软件工程', '24');
INSERT INTO `student` VALUES ('2', 'xy', '男', '计算机', '21');
INSERT INTO `student` VALUES ('3', 'cyy', '男', '体育', '13');
INSERT INTO `student` VALUES ('4', 'swt', '男', '数字媒体', '5');
INSERT INTO `student` VALUES ('5', 'lwz', '男', '煤炭专业', '30');
INSERT INTO `student` VALUES ('6', 'tjx', '男', '软件工程', '19');
INSERT INTO `student` VALUES ('7', 'zy', '女', '软件工程', '23');
INSERT INTO `student` VALUES ('8', 'xr', '女', '移动互联', '25');
INSERT INTO `student` VALUES ('9', 'gx', '女', '移动互联', '25');

课程表：

/*
Navicat MySQL Data Transfer

Source Server         : aaa
Source Server Version : 80012
Source Host           : localhost:3306
Source Database       : kaoyan

Target Server Type    : MYSQL
Target Server Version : 80012
File Encoding         : 65001

Date: 2020-02-17 12:13:14
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for course
-- ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
  `Cno` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `Cname` varchar(10) DEFAULT NULL,
  `Cpno` int(11) DEFAULT NULL,
  `Ccredit` int(11) DEFAULT NULL,
  PRIMARY KEY (`Cno`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

-- ----------------------------
-- Records of course
-- ----------------------------
INSERT INTO `course` VALUES ('1', '软件工程导论', '10', '5');
INSERT INTO `course` VALUES ('2', '高数1', '0', '5');
INSERT INTO `course` VALUES ('3', '高数2', '2', '5');
INSERT INTO `course` VALUES ('4', '体育', '9', '3');
INSERT INTO `course` VALUES ('5', '羽毛球', '8', '2');
INSERT INTO `course` VALUES ('6', '足球', '7', '2');
INSERT INTO `course` VALUES ('7', '经济学', '6', '2');
INSERT INTO `course` VALUES ('8', '心理学', '5', '1');

学生选课：

/*
Navicat MySQL Data Transfer

Source Server         : aaa
Source Server Version : 80012
Source Host           : localhost:3306
Source Database       : kaoyan

Target Server Type    : MYSQL
Target Server Version : 80012
File Encoding         : 65001

Date: 2020-02-17 12:13:51
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for sc
-- ----------------------------
DROP TABLE IF EXISTS `sc`;
CREATE TABLE `sc` (
  `Sno` int(10) unsigned NOT NULL,
  `Cno` int(10) unsigned NOT NULL,
  `Grade` int(11) NOT NULL,
  PRIMARY KEY (`Sno`,`Cno`),
  KEY `Cno` (`Cno`),
  CONSTRAINT `sc_ibfk_1` FOREIGN KEY (`Sno`) REFERENCES `student` (`sno`),
  CONSTRAINT `sc_ibfk_2` FOREIGN KEY (`Cno`) REFERENCES `course` (`cno`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

-- ----------------------------
-- Records of sc
-- ----------------------------
INSERT INTO `sc` VALUES ('1', '1', '90');
INSERT INTO `sc` VALUES ('1', '2', '80');
INSERT INTO `sc` VALUES ('1', '3', '60');
INSERT INTO `sc` VALUES ('1', '4', '60');
INSERT INTO `sc` VALUES ('1', '5', '60');
INSERT INTO `sc` VALUES ('1', '6', '50');
INSERT INTO `sc` VALUES ('1', '7', '60');
INSERT INTO `sc` VALUES ('1', '8', '30');
INSERT INTO `sc` VALUES ('2', '8', '50');
INSERT INTO `sc` VALUES ('3', '7', '50');
INSERT INTO `sc` VALUES ('4', '6', '50');
INSERT INTO `sc` VALUES ('5', '5', '75');
INSERT INTO `sc` VALUES ('6', '4', '95');
INSERT INTO `sc` VALUES ('7', '5', '90');
INSERT INTO `sc` VALUES ('8', '2', '78');
INSERT INTO `sc` VALUES ('8', '3', '90');
INSERT INTO `sc` VALUES ('9', '1', '66');

建表完成后开始练习：

例1 查询全体学生的学号和姓名。