MySQL查詢練習題一

新建數據表需求如下

 

 

 

 

 

 1.創建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.為student表和score表增加記錄

向student表插入記錄的INSERT語句如下：

INSERT INTO student VALUES( 901,'張老大', '男',1985,'計算機系', '北京市海淀區');

INSERT INTO student VALUES( 902,'張老二', '男',1986,'中文系', '北京市昌平區');

INSERT INTO student VALUES( 903,'張三', '女',1990,'中文系', '湖南省永州市');

INSERT INTO student VALUES( 904,'李四', '男',1990,'英語系', '遼寧省阜新市');

INSERT INTO student VALUES( 905,'王五', '女',1991,'英語系', '福建省廈門市');

INSERT INTO student VALUES( 906,'王六', '男',1988,'計算機系', '湖南省衡陽市');

向score表插入記錄的INSERT語句如下：

INSERT INTO score VALUES(NULL,901, '計算機',98);

INSERT INTO score VALUES(NULL,901, '英語', 80);

INSERT INTO score VALUES(NULL,902, '計算機',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, '計算機',70);

INSERT INTO score VALUES(NULL,904, '英語',92);

INSERT INTO score VALUES(NULL,905, '英語',94);

INSERT INTO score VALUES(NULL,906, '計算機',90);

INSERT INTO score VALUES(NULL,906, '英語',85);

3.查詢student表的所有記錄

SELECT * FROM student;

4.查詢student表的第2條到4條記錄

SELECT * FROM student LIMIT 1,3;

5.從student表查詢所有學生的學號（id）、姓名（name）和院系（department）的信息

SELECT id,name,department FROM student;

6.從student表中查詢計算機系和英語系的學生的信息

SELECT * FROM student WHERE department IN ('計算機系','英語系');

7.從student表中查詢年齡18~22歲的學生信息

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.從student表中查詢每個院系有多少人 

 SELECT department, COUNT(id) FROM student GROUP BY department;

9.從score表中查詢每個科目的最高分

SELECT c_name,MAX(grade) FROM score GROUP BY c_name;

10.查詢李四的考試科目（c_name）和考試成績（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.用連接的方式查詢所有學生的信息和考試信息

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

12.計算每個學生的總成績

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

13.計算每個考試科目的平均成績

SELECT c_name,AVG(grade) FROM score GROUP BY c_name;

14.查詢計算機成績低於95的學生信息

 SELECT * FROM student WHERE id IN (SELECT stu_id FROM score WHERE c_name="計算機" and grade<95);

15.查詢同時參加計算機和英語考試的學生的信息

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=  '計算機') AND c_name= '英語' );

方法二：

SELECT a.* FROM student a ,score b ,score c WHERE a.id=b.stu_id AND b.c_name='計算機' AND a.id=c.stu_id AND c.c_name='英語';

16.將計算機考試成績按從高到低進行排序

SELECT stu_id, grade FROM score WHERE c_name= '計算機' ORDER BY grade DESC;

17.從student表和score表中查詢出學生的學號，然后合並查詢結果

SELECT id  FROM student UNION SELECT stu_id  FROM score;

18.查詢姓張或者姓王的同學的姓名、院系和考試科目及成績

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

19.查詢都是湖南的學生的姓名、年齡、院系和考試科目及成績

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;