Joining three tables using MySQL

PHP Ferrari picture PHP Ferrari · Sep 14, 2010 · Viewed 327.5k times · Source

I have three tables named

**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

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

I build following query

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

But it does not return the required result...

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

And wants to get this result:

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

Answer

D'Arcy Rittich picture D'Arcy Rittich · Sep 14, 2010

Use ANSI syntax and it will be a lot more clear how you are joining the tables:

SELECT s.name as Student, c.name as Course 
FROM student s
    INNER JOIN bridge b ON s.id = b.sid
    INNER JOIN course c ON b.cid  = c.id 
ORDER BY s.name