16.多表联合查询

mysql> create database oldboy;
Query OK, 1 row affected (0.01 s
mysql> use oldboy
Database changed
创建学生表
create table student(
Sno int(10) NOT NULL COMMENT ‘学号‘,
Sname varchar(16) NOT NULL COMMENT ‘姓名‘,
Ssex char(2) NOT NULL COMMENT ‘性别‘,
Sage tinyint(2) NOT NULL default ‘0‘ COMMENT ‘学生年龄‘,
Sdept varchar(16) default NULL COMMENT ‘学生所在系别‘,
PRIMARY KEY (Sno) ,
key index_Sname (Sname)
);

insert into student values(0001,‘宏志‘,‘男‘,30,‘计算机网络‘);
insert into student values(0002,‘王硕‘,‘男‘,30,‘computer application‘);
insert into student values(0003,‘oldboy‘,‘男‘,28,‘物流管理‘);
insert into student values(0004,‘脉动‘,‘男‘,29,‘computer application‘);
insert into student values(0005,‘oldgirl‘,‘女‘,26,‘计算机科学与技术‘);
insert into student values(0006,‘莹莹‘,‘女‘,22,‘护士‘);

create table course(

Cno int(10) NOT NULL COMMENT ‘课程号‘,
Cname varchar(16) NOT NULL COMMENT ‘课程名‘,
Ccredit tinyint(2) NOT NULL COMMENT ‘学分‘,
PRIMARY KEY (Cno)
);

insert into course values(1001,‘linux 中高级运维‘,‘3‘);
insert into course values(1002,‘linux 中高级架构师‘,‘5‘);
insert into course values(1003,‘mysql 高级 Dba‘,‘4‘);
insert into course values(1004,‘python 运维开发‘,‘4‘);
insert into course values(1005,‘java web 开发‘,‘3‘);

create table sc(
Scid int(12) not null auto_increment COMMENT ‘主键‘,
Cno int(10) not null COMMENT ‘课程号‘,
Sno int(10) not null COMMENT ‘学号‘,
Grade tinyint(2) not null COMMENT ‘学生成绩‘,
PRIMARY KEY(Scid)
);

insert into sc(Sno,Cno,Grade) values(0001,1001,4);
insert into sc(Sno,Cno,Grade) values(0001,1002,3);
insert into sc(Sno,Cno,Grade) values(0001,1003,1);
insert into sc(Sno,Cno,Grade) values(0001,1004,6);
insert into sc(Sno,Cno,Grade) values(0002,1001,3);
insert into sc(Sno,Cno,Grade) values(0002,1002,2);
insert into sc(Sno,Cno,Grade) values(0002,1003,2);
insert into sc(Sno,Cno,Grade) values(0002,1004,8);
insert into sc(Sno,Cno,Grade) values(0003,1001,4);
insert into sc(Sno,Cno,Grade) values(0003,1002,4);
insert into sc(Sno,Cno,Grade) values(0003,1003,2);
insert into sc(Sno,Cno,Grade) values(0003,1004,8);
insert into sc(Sno,Cno,Grade) values(0004,1001,1);
insert into sc(Sno,Cno,Grade) values(0004,1002,1);
insert into sc(Sno,Cno,Grade) values(0004,1003,2);
insert into sc(Sno,Cno,Grade) values(0004,1004,3);
insert into sc(Sno,Cno,Grade) values(0005,1001,5);
insert into sc(Sno,Cno,Grade) values(0005,1002,3);
insert into sc(Sno,Cno,Grade) values(0005,1003,2);
insert into sc(Sno,Cno,Grade) values(0005,1004,9);

mysql> select student.Sno,student.Sname,course.Cname,sc.Grade from student,course,sc where
student.Sno=sc.Sno and course.Cno=sc.Cno order by Sno;
+-----+---------+-------------------------+-------+
| Sno | Sname | Cname | Grade |
+-----+---------+-------------------------+-------+
| 1 | 宏志 | mysql 高级 Dba | 1 |
| 1 | 宏志 | python 运维开发 | 6 |
| 1 | 宏志 | linux 中高级运维 | 4 |
| 1 | 宏志 | linux 中高级架构师 | 3 |
| 2 | 王硕 | linux 中高级运维 | 3 |
| 2 | 王硕 | linux 中高级架构师 | 2 |
| 2 | 王硕 | mysql 高级 Dba | 2 |
| 2 | 王硕 | python 运维开发 | 8 |
| 3 | oldboy | mysql 高级 Dba | 2 |
| 3 | oldboy | python 运维开发 | 8 |
| 3 | oldboy | linux 中高级运维 | 4 |
| 3 | oldboy | linux 中高级架构师 | 4 |
| 4 | 脉动 | linux 中高级运维 | 1 |
| 4 | 脉动 | linux 中高级架构师 | 1 |
| 4 | 脉动 | mysql 高级 Dba | 2 |
| 4 | 脉动 | python 运维开发 | 3 |
| 5 | oldgirl | python 运维开发 | 9 |
| 5 | oldgirl | linux 中高级运维 | 5 |
| 5 | oldgirl | linux 中高级架构师 | 3 |
| 5 | oldgirl | mysql 高级 Dba | 2 |
+-----+---------+-------------------------+-------+
20 rows in set (0.00 sec)