MySQL多表关联查询习题

news2024/12/26 10:44:04

一、素材

-- Active: 1714203732007@@127.0.0.1@3306@db_stu
-- 1.创建student和score表
CREATE TABLE student (
id INT(10) NOT NULL UNIQUE PRIMARY KEY ,
name VARCHAR(20) NOT NULL ,
sex VARCHAR(4) ,
birth YEAR,
department VARCHAR(20) ,
address VARCHAR(50)
);
-- 创建score表。SQL代码如下：
CREATE TABLE score (
id INT(10) NOT NULL UNIQUE PRIMARY KEY AUTO_INCREMENT ,
stu_id INT(10) NOT NULL ,
c_name VARCHAR(20) ,
grade INT(10)
);
-- 2.为student表和score表增加记录
-- 向student表插入记录的INSERT语句如下：
INSERT INTO student VALUES( 901,'张老大', '男',1985,'计算机系', '北京市海淀区');
INSERT INTO student VALUES( 902,'张老二', '男',1986,'中文系', '北京市昌平区');
INSERT INTO student VALUES( 903,'张三', '女',1990,'中文系', '湖南省永州市');
INSERT INTO student VALUES( 904,'李四', '男',1990,'英语系', '辽宁省阜新市');
INSERT INTO student VALUES( 905,'王五', '女',1991,'英语系', '福建省厦门市');
INSERT INTO student VALUES( 906,'王六', '男',1988,'计算机系', '湖南省衡阳市');
-- 向score表插入记录的INSERT语句如下：
INSERT INTO score VALUES(NULL,901, '计算机',98);
INSERT INTO score VALUES(NULL,901, '英语', 80);
INSERT INTO score VALUES(NULL,902, '计算机',65);
INSERT INTO score VALUES(NULL,902, '中文',88);
INSERT INTO score VALUES(NULL,903, '中文',95);
INSERT INTO score VALUES(NULL,904, '计算机',70);
INSERT INTO score VALUES(NULL,904, '英语',92);
INSERT INTO score VALUES(NULL,905, '英语',94);
INSERT INTO score VALUES(NULL,906, '计算机',90);
INSERT INTO score VALUES(NULL,906, '英语',85);

查看数据是否插入

二、习题

SQL语句

-- 作业
-- 3.查询student表的所有记录
select * from student;
-- 4.查询student表的第2条到4条记录
select * from student limit 2,4;
-- 5.从student表查询所有学生的学号（id）、姓名（name）和院系（department）的信息
select id,name,department from student;
-- 6.从student表中查询计算机系和英语系的学生的信息
select * from student where department='计算机系' OR department='英语系';
-- 7.从student表中查询年龄18~22岁的学生信息
select * from student where 2024-birth>=18 AND 2024-birth<=22;
-- 8.从student表中查询每个院系有多少人
select department,COUNT(*) as 总人数 from student GROUP BY department;
-- 9.从score表中查询每个科目的最高分
select c_name,MAX(grade) from score GROUP BY c_name;
-- 10.查询李四的考试科目（c_name）和考试成绩（grade）
select c_name,grade from score where stu_id=(select id from student where name='李四');
-- 11.用连接的方式查询所有学生的信息和考试信息
select * from student CROSS JOIN score;
-- 12.计算每个学生的总成绩
select student.id,student.name,SUM(score.grade) from student JOIN score ON student.id=score.stu_id GROUP BY  student.id,student.name;
-- 13.计算每个考试科目的平均成绩
select c_name,AVG(grade) from score GROUP BY c_name;
-- 14.查询计算机成绩低于95的学生信息
select * from student JOIN score on student.id=score.stu_id where student.department='计算机系' and score.grade<=95;
-- 15.查询同时参加计算机和英语考试的学生的信息
select student.* from student JOIN score sc1 on student.id=sc1.stu_id and sc1.c_name='计算机' JOIN score sc2 on student.id=sc2.stu_id and sc2.c_name='英语';
-- 16.将计算机考试成绩按从高到低进行排序
select student.id,student.name,score.grade from student JOIN score ON student.id=score.stu_id where score.c_name='计算机' ORDER BY grade DESC;
-- 17.从student表和score表中查询出学生的学号，然后合并查询结果
select id from student UNION all SELECT stu_id from score;
-- 18.查询姓张或者姓王的同学的姓名、院系和考试科目及成绩
select  student.name,student.department,score.c_name,score.grade
from student JOIN score ON student.id=score.stu_id
where student.name like '张%' or student.name like '王%';
-- 19.查询都是湖南的学生的姓名、年龄、院系和考试科目及成绩
SELECT student.name,2024-(student.birth),student.department,score.c_name,score.grade,student.address
from student JOIN score on student.id=score.stu_id
where student.address like '%湖南%';