一尘不染

使用MySQL连接三个表

mysql

我有三个表名为

**Student Table**
-------------
id    name
-------------
1     ali
2     ahmed
3     john
4     king

**Course Table**
-------------
id    name
-------------
1     physic
2     maths
3     computer
4     chemistry

**Bridge**
-------------
sid    cid
-------------
1     1
1     2
1     3
1     4
2     1
2     2
3     3
3     4
4     1
4     2

现在要显示学生姓名和他所学习的课程名称,

**Result**
---------------------------
Student        Course
---------------------------
ahmed         physic
ahmed         maths
ahmed         computer
ahmed         chemistry
ali           physic
ali           maths
john          computer
john          chemistry
king          physic
king          maths

我建立以下查询

select s.name as Student, c.name as Course from student s, course c join bridge b on c.id = b.cid order by s.name

但是它不会返回所需的结果…

如果我想找到谁是其他经理,那么归一化表格将是什么:

**employee**
-------------------
id        name
-------------------
1         ali
2         king
3         mak
4         sam
5         jon

**manage**
--------------
mid      eid
--------------
1         2
1         3
3         4
4         5

并希望得到以下结果:

**result**
--------------------
Manager      Staff
--------------------
ali          king
ali          mak
mak          sam
sam          jon

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2020-05-17

共1个答案

一尘不染

只需使用:

select s.name "Student", c.name "Course"
from student s, bridge b, course c
where b.sid = s.sid and b.cid = c.cid
2020-05-17