多表查询经典例子

create table students (sid char(8) primary key not null comment ‘学号’,name varchar(20) not null comment ‘学生姓名’,sex char(2) not null comment ‘性别’)engine=myisam default charset=utf8 insert into students (sid,name,sex) values (‘20130001′,’张三’,’男’); insert into students (sid,name,sex) values (‘20130002′,’赵四’,’男’); insert into students (sid,name,sex) values (‘20130005′,’李四’,’男’); insert into students (sid,name,sex) values (‘20130006′,’小红’,’女’); insert into students (sid,name,sex) values (‘20130004′,’小燕’,’女’); insert into students (sid,name,sex) values (‘20130007′,’苍老师’,’女’);

create table scourse (cid int(8) primary key auto_increment comment ‘课程号’, cname varchar(20) not null comment ‘课程名称’, scredit float(10,2) not null comment ‘该课程学分’ ) engine=myisam default charset=utf8

insert into scourse (cname,scredit) values (‘C语言’,6); insert into scourse (cname,scredit) value (‘计算机编程’,7); insert into scourse (cname,scredit) value (‘计算机应用’,10); insert into scourse (cname,scredit) value (‘C++’,10); create table sc (sid char(8) not null comment ‘学号’,cid int(8) not null comment ‘该学生选择的课程号’,score float(10,2) null comment ‘该学生该课程实际得分’) engine = myisam default charset =utf8 insert into sc (sid,cid,score) value (‘20130001’,1,5); insert into sc (sid,cid,score) value (‘20130001’,3,8); insert into sc (sid,cid,score) value (‘20130001’,4,9); insert into sc (sid,cid,score) value (‘20130004’,1,2); insert into sc (sid,cid,score) value (‘20130004’,3,2); insert into sc (sid,cid,score) value (‘20130004’,2,6); insert into sc (sid,cid,score) value (‘20130002’,3,6); insert into sc (sid,cid,score) value (‘20130005’,4,6); insert into sc (sid,cid,score) value (‘20130007’,1,6); insert into sc (sid,cid,score) value (‘20130006’,3,6); insert into sc (sid,cid,score) value (‘20130003’,2,7);

附件：多表查询