SQL经典查询语句

创建学生表student，成绩表sc，课程表course

create or replace table student(
 sid     int(11) primary key not null,
 sname   char(25) not null,
 age     int(11) not null,
 sex     char(2) not null,
 department char(40) ,
 address  char(200) ,
 birthplace  varchar(256)
);

create or replace table sc(
  sid   int(11) not null,
  cid   int(11) not null,
  grade int(11) 
);

create or replace table course(
  cid    int(11) not null primary key default 4,
  cname  char(40),
  teacher  char(40)
);

#以下是插入课程表的数据
delete from course ;
insert into course values('8108001','math','sandy');
insert into course values('8108002','english','sherry');
insert into course values('8108003','computer','sandy');
insert into course values('8108004','web','sandy');
insert into course values('8108005','java','sandy');
insert into course values('8108006','C languge','sherry');
insert into course values('8108007','python','xiaozhu');
insert into course values('8108008','testing','xiaozhu');
insert into course values('8108009','linux','sherry');
insert into course values('8108010','shell','sherry');
#右联结插入数据----begin
insert into course values('8108020','shell','sherry');
insert into course values('8108021','shell','sherry');
insert into course values('8108022','shell','sherry');
insert into course values('8108023','shell','sherry');
insert into course values('8108024','shell','sherry');
#----end

#以下是插入成绩级表的数据

delete from sc;
insert into sc values('3108001','8108010','90');
insert into sc values('3108001','8108003','67');
insert into sc values('3108002','8108003','54');
insert into sc values('3108002','8108010','84');
insert into sc values('3108003','8108003','78');
insert into sc values('3108004','8108004','89');
insert into sc values('3108005','8108006','56');
insert into sc values('3108006','8108005','60');
insert into sc values('3108007','8108004','79');
insert into sc values('3108008','8108008','89');
insert into sc values('3108009','8108002','46');
insert into sc values('3108010','8108003','87');
insert into sc values('3108011','8108001','85');
insert into sc values('3108011','8108002','81');
insert into sc values('3108012','8108001','97');
insert into sc values('3108012','8108002','55');
insert into sc values('3108013','8108002','86');
insert into sc values('3108013','8108001','71');
insert into sc values('3108014','8108002','69');
insert into sc values('3108014','8108001','78');
insert into sc values('3108015','8108002','67');
insert into sc values('3108016','8108001','85');
#左联结插入的数据
insert into sc values('3108016','8108013','85');
insert into sc values('3108016','8108012','85');
insert into sc values('3108016','8108011','85');
insert into sc values('3108016','8108012','85');

insert into sc values('3108016','8108002','80');
insert into sc values('3108016','8108006','79');
insert into sc values('3108016','8108009','36');
insert into sc values('3108016','8108010','78');
insert into sc values('3108016','8108020','88');
insert into sc values('3108016','8108021','83');
insert into sc values('3108016','8108022','86');
insert into sc values('3108016','8108023','75');
insert into sc values('3108016','8108024','78');
#----end

#以下是插入学生信息数据

delete from student;
insert into student values('3108001','wang min',21,'f','computer-tec','zhongshan road','jiangsu');
insert into student values('3108002','jidu',20,'m','english','zhongshan road','fujian');
insert into student values('3108003','wangqing',19,'f','computer-tec','zhongshan road','jiangsu');
insert into student values('3108004','liuxin',23,'f','chinese','zhongshan road','shanghai');
insert into student values('3108005','ligu',22,'f','computer-tec','zhongshan road','jiangsu');
insert into student values('3108006','songjia',19,'m','english','zhongshan road','jiangsu');
insert into student values('3108007','huamao',20,'f','chinese','zhongshan road','shanghai');
insert into student values('3108008','zhujiao',21,'f','english','zhongshan road','jiangsu');
insert into student values('3108009','wuyi',23,'m','computer-tec','zhongshan road','jiangsu');
insert into student values('3108010','jilian',18,'f','chinese','zhongshan road','hunan');
insert into student values('3108011','linbiao',22,'m','computer-tec','zhongshan road','jiangsu');
insert into student values('3108012','maoguai',21,'m','english','zhongshan road','fujian');
insert into student values('3108013','rongqi',23,'m','computer-tec','zhongshan road','jiangsu');
insert into student values('3108014','sangzi',20,'f','chinese','zhongshan road','hunan');
insert into student values('3108015','surui',16,'f','computer-tec','zhongshan road','fujian');
insert into student values('3108016','liushaoqi',24,'m','english','zhongshan road','hunan');

练习题

1. sandy老师所教的课程号、课程名称；
2. 年龄大于20岁的女学生的学号和姓名；
3. 在学生表中按性别排序，且男在前女在后显示记录。
4. “wuyi”所选修的全部课程名称；
5. 所有成绩都在80分以上的学生姓名及所在系；
6. 没有选修“english”课的学生的姓名；
7. 与“jilian”同乡的男生姓名及所在系；
8. 英语成绩比数学成绩好的学生;
9. 选修同一门课程时，女生比所有男生成绩都好的学生名单；
10. 至少选修两门及以上课程的学生姓名、性别；
11. 选修了sandy老师所讲课程的学生人数；
12. 所讲课程的学生;
13. 本校学生中有学生姓名/性别重复的同学，请编写脚本查出本校所有学生的信息，显示学号，姓名，性别，总成绩，对于姓名/性别重复的学生信息只取总成绩最高的那一条记录。
14. “english”课程得最高分的学生姓名、性别、所在系；
15. 新建一个表‘dt’,格式如下:

year1	mon	account

达到效果如下：

处理前的数据:

year1	mon	account
1991	1	1.1
1991	2	1.2
1991	3	1.3
1991	4	1.4
1992	1	2.1
1992	2	2.2
1992	3	2.3
1992	4	2.4

处理后的数据: year1	m1	m2	m3	m4
1991	1.10...	1.20...	1.29...	1.39999997...
1992	2.09...	2.20...	2.29...	2.40000009...