MySQL查询练习题一

新建数据表需求如下

 

 

 

 

 

 1.创建student和score表

CREATE TABLE student (
id int(10) ,
name varchar(20) NOT NULL,
sex varchar(4) ,
birth year(4) ,
department varchar(20) NOT NULL,
address varchar(50) ,
PRIMARY KEY (id)
)

CREATE TABLE score (
id int(10) NOT NULL AUTO_INCREMENT,
stu_id int(10) NOT NULL,
c_name varchar(20) DEFAULT NULL,
grade int(10) DEFAULT NULL,
PRIMARY KEY (id),
UNIQUE KEY id (id)
)

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);

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 1,3;

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 IN ('计算机系','英语系');

7.从student表中查询年龄18~22岁的学生信息

方法一：

SELECT id,name,sex,2013-birth AS age,department,address FROM student WHERE 2013-birth BETWEEN  18 AND 22;

方法二：

 SELECT id,name,sex,2013-birth AS age,department,address FROM student WHERE 2013-birth>=18 AND 2013-birth<=22;

8.从student表中查询每个院系有多少人 

 SELECT department, COUNT(id) 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）

方法一：

SELECT c_name, grade FROM score WHERE stu_id= (SELECT id FROM student WHERE name= '李四' );

方法二：

SELECT c_name, grade FROM score WHERE stu_id IN (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 student.id,name,sex,birth,department,address,c_name,grade FROM student,score WHERE student.id=score.stu_id;

12.计算每个学生的总成绩

SELECT student.id,name,SUM(grade) FROM student,score WHERE student.id=score.stu_id GROUP BY id;

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 WHERE id IN (SELECT stu_id FROM score WHERE c_name="计算机" and grade<95);

15.查询同时参加计算机和英语考试的学生的信息

方法一：

 SELECT *  FROM student WHERE id =ANY ( SELECT stu_id FROM score WHERE stu_id IN (SELECT stu_id FROM score WHERE c_name=  '计算机') AND c_name= '英语' );

方法二：

SELECT a.* FROM student a ,score b ,score c WHERE a.id=b.stu_id AND b.c_name='计算机' AND a.id=c.stu_id AND c.c_name='英语';

16.将计算机考试成绩按从高到低进行排序

SELECT stu_id, grade FROM score WHERE 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 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.id, name,sex,birth,department, address, c_name,grade FROM student, score WHERE (name LIKE  '张%'  OR name LIKE  '王%') AND student.id=score.stu_id ;

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.id, name,sex,birth,department, address, c_name,grade FROM student, score WHERE address LIKE '湖南%'   AND student.id=score.stu_id;