广州哪里有外贸网站/星巴克网络营销案例分析

表结构：

Student学生表(学号、姓名、性别、年龄、编辑)

Course课程表(编号、课程名称)

sc选课表(选课编号、学号、课程编号、成绩)

(1)写一个SQL语句，查询选修了“计算机原理”的学生学号和姓名

(2)写一个SQL语句，查询“小明”同学选修的课程名称

(3)写一个SQL语句，查询选修了5门课程的学生学号和姓名

答案：

(1)

select student.stu_no,student.stu_name

from student,course,sc

where course.c_no=sc.c_no and sc.stu_no=student.stu_no and course.c_name='计算机原理';

(2)

select course.c_name,student.stu_name

from student,course,sc

where student.stu_name='小明' and student.stu_no=sc.stu_no and sc.c_no=course.c_no;

(3)

select student.stu_no,stu_name

from student,course,sc

where student.stu_no=sc.stu_no and sc.c_no=course.c_no

group by student.stu_no

having count(*)=5

建表及插入数据可参考如下语句：

create table student(

stu_no int,

stu_name varchar(10),

sex char(1),

age int(3),

edit varchar(20)

);

insert into student values

(1,'wang','男',21,'hello'),

(2,'小明','女',22,'haha2'),

(3,'hu','女',23,'haha3'),

(4,'li','男',25,'haha4');

create table course(

c_no int,

c_name varchar(10)

);

insert into course values

(1,'计算机原理'),

(2,'java'),

(3,'c'),

(4,'php'),

(5,'py');

create table sc(

sc_no int,

stu_no int,

c_no int,

score int(3)

);

insert into sc values

(1,1,1,80),

(2,2,2,90),

(3,2,1,85),

(4,2,3,70),

(5,2,4,95),

(6,2,5,89);