問題描述

我有三個名為的表

**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

現在顯示學生姓名和他學習的課程名稱，

Now to show the student name with the course name which he had studied like,

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

我構建以下查詢

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

但它沒有返回所需的結果...

But it does not return the required result...

如果我想找到誰是經理而不是其他人，那么規范化形式會是什么:

And what would be for normalized form, if I want to find who is manager over other:

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

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

并且想要得到這個結果:

And wants to get this result:

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

推薦答案

簡單使用:

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

這篇關于使用 MySQL 連接三個表的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！