基本的SQL语句练习（学生课程表）

创建表

DROP TABLE IF EXISTS student;
CREATE TABLE student(
sno int auto_increment primary key,
sname varchar(8),
ssex varchar(3),
sage int ,
sclass varchar(6)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO student(sname,ssex,sage,sclass) VALUES('李勇','男',20,'y01');
INSERT INTO student(sname,ssex,sage,sclass) VALUES('刘晨','男',21,'y02');
INSERT INTO student(sname,ssex,sage,sclass) VALUES('王敏','女',19,'y02');
INSERT INTO student(sname,ssex,sage,sclass) VALUES('张力','男',25,'y05');
DROP TABLE IF EXISTS course;
CREATE TABLE course(
cno int auto_increment primary key,
cname varchar(20),
ccredit int
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO course(cname,ccredit) VALUES('C语言',5);
INSERT INTO course(cname,ccredit) VALUES('数据库',5);
INSERT INTO course(cname,ccredit) VALUES('开发模式_VB',5);
DROP TABLE IF EXISTS sc;
CREATE TABLE sc(
sno int references student(sno) on delete cascade,
cno int references course(cno) on delete cascade,
grade int
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO sc VALUES(1,1,90);
INSERT INTO sc VALUES(1,2,95);
INSERT INTO sc VALUES(2,1,55);
INSERT INTO sc VALUES(4,3,null);

1、查出全体同学的学号、姓名

select sno,sname from student;

2、查询全体同学的姓名学号班级（按顺序输出）

select sname,sno,sclass from student;

3、查询全体同学的记录（显示所有行）

select * from student;

4、查询全体同学的姓名及出生年份

select sname,(2010-sage) as '出生年份' from student ;

5、查询全体同学姓名出生年份班级（班级要用小写字母lower函数）

select sname,2010-sage as '出生年份',lower(sclass) from student;

6、查询全体同学的姓名/出生年份/所在班级列为YearOfBirth

select sname,2010-sage YearOfBirth,sclass from student;

7、查询选中学员的所在班级并且去掉重复行用distinct

select distinct sclass from student;

8、查询Y02班全体同学名单

select * from student where sclass='y02';

9、查询所有年龄在20岁一下的同学姓名及年龄

select sname,sage from student where sage<20;

10、查询考试不及格的同学的姓名及成绩

select s.sname,sc.grade from student s,sc where s.sno = sc.sno and sc.grade <60;

11、查询年龄在19－20岁（包括19、20）之间的同学姓名、班级、年龄

select sname,sclass,sage from student where sage in (19,20);（19、20 比较特殊选项少可以使用 in）

select sname,sclass,sage from student where sage between 19 and 20;

select sname,sclass,sage from student where sage>=19 and sage<=20;

12、查询年龄不在19－20岁之间的同学姓名、班级、年龄

select sname,sclass,sage from student where sage not in (19,20);

select sname,sclass,sage from student where sage not between 19 and 20;

select sname,sclass,sage from student where sage<19 or sage>20;

13、查询y02班级和y05班的同学的姓名、性别

select sname,sclass from student where sclass in ('y02','y05');

select sname,sclass from student where sclass='y02' or sclass='y05';

14、查询不是y02或者y05班的同学的姓名、性别

select sname,sage from student where sclass not in('y02','y05');

select sname,sage from student where sclass!='y02' and sclass!='y05';

select sname,sage from student where not sclass='y02' and not sclass='y05';

15、查所有姓刘的同学的姓名、学号、性别( " % "表示一个或者多个，" _ "表示只占一个字符)

select sname,sno,ssex from student where sname like'刘%';

16、查所有姓张且全名只有2个汉子的同学的所有信息

select * from student where sname like'张_';

17、某些学生未考试查缺成绩的同学的学号和课程号

select sno,cno,grade from sc where grade is null;

18、查询所有成绩的同学的学号、课程号和成绩

select sno,cno,grade from sc where grade is not null;

19、查y02班年龄在20岁一下的姓名和年龄

select sname,sage from student where sclass='y02' and sage<20;

20、查选修1号课程的同学的学号和成绩，按成绩降序排序

select sno,grade from sc where cno=1 order by grade desc;

21、查全体同学信息查询结果按所在班级的班级名称按降序排列，同班同学按年龄升序排列

select * from student order by sclass desc,sage asc;

22、查询学员的总人数

select count(sno) from student;

23、查选修课程学院人数

select count(*) from sc;

24、统计1号课的学院平均成绩

select avg(grade) 平均成绩 from sc where cno=1;

25、查选修1号课和同学最高成绩

select max(grade) from sc where cno=1;

26、求各个课程号及相应选课人数

select cno,count(*) 选课人数 from sc group by cno;

27、查选取1门以上课程的同学学号和课程个数

select sno,count(cno) from sc group by sno having count(cno)>1;

28、查每个学员及其选修课程情况

select sno,cno from sc;

29、查每个学员及其选修课程情况对没有选课的也要输出其姓名、学号、性别、班级(注意：是作外连接student是主表)

select st.sname,st.sno,st.ssex,st.sclass,sc.cno,sc.grade

from student st left join sc on

st.sno = sc.sno order by st.sname;

30、查选取2号课程且成绩在90分以上的同学

select * from sc where cno=2 and grade>90;

31、查询每个同学学号姓名，选课程名称及其成绩

select stu.sno,stu.sname,c.cname,sc.grade

from student stu join sc on stu.sno = sc.sno

join course c on c.cno = sc.cno;

或者

select stu.sno,stu.sname,c.cname,sc.grade

from student stu,course c,sc

where stu.sno=sc.sno and c.cno= sc.cno

order by sc.cno desc;

32、查与刘晨在一个班的同学

select * from student where sclass=(select sclass from student where sname='刘晨');

33、选取C语言的同学学号和姓名

select s.sno,s.sname

from student s join sc on s.sno=sc.sno

join course c on sc.cno=c.cno

where c.cname='C语言';

或者

select sno,sname from student where sno in

(select sno from sc where cno in

(select cno from course where cname='C语言'));

34、查其他班级中比y02班某一同学大的同学姓名和年龄

select sname,sage from student

where sclass<>'y02' and

sage > (select min(sage) from student where sclass='y02');

或者（加入 any 关键字）

select sname,sage from student

where sclass<>'y02' and

sage >any (select sage from student where sclass='y02');

35、查其他班中比y02班同学全部都大的同学姓名和年龄

select sname,sage from student

where sclass!='y02' and

sage > (select max(sage) from student where sclass='y02');

或者（加入 all 关键字）

select sname,sage from student

where sclass!='y02' and

sage >all (select sage from student where sclass='y02');

36、查选取1号课程的学员的姓名

（在与查询的集合的包含关系时，最好使用 in 、any、all）

select s.sname from student s,sc

where s.sno = sc.sno and sc.cno=1;

或者（子查询）

select sname from student where sno in

(select sno from sc where cno=1);

37、查没有选取1号课程的学员的姓名(注意：要过滤已经选取过1号的同学，因为可能某同学多选修课程)

说明：如果是过滤集合，就只能用 in/all/any

select sname from student where sno not in

(select sno from sc where cno=1);

38、查y02班同学及年龄不大于19岁的学员（union）

select * from student where sclass='y02' union

select * from student where sage<=19;

解析：y02班级的同学与全年纪年龄不大于19岁的学生，而（sage<=19 and sclass='y02'）表示为

y02班级同学“且”年龄不大于19岁的同学，与题意不符。所以下面的语句是错误的，因为范围没有确定好

select * from student where sclass='y02' and sage<=19;

说明：union 用来两个集合求并集（合并两个集合，并且除去重复的记录）

39、查询选取1号课程或者2号课程的同学学号

select distinct sno from sc where cno=1 or cno=2;

或者

select distinct sno from sc where cno in (1,2);

40、将4号学员的年龄改为23岁

update student set sage=23 where sno=4;

41、将所有同学的年龄增加1岁

update student set sage=sage+1;

42、y02班的同学的成绩改为100

update sc set grade=100 where sno in (select sno from student where sclass='y02');

43、删除学号为1的同学记录

delete from student where sno=1;