Using joins with session variable

bharanidharanit · #1 (**permalink**) 01-27-10, 04:13

Hi,
I want to create a join with id from $userid.
With my 2 tables,
users
id, username
1 a
2 b
3 c
friends
id, userid, friendid
1 1 2
2 1 3
3 3 2
My session variable $userid holds a userid.
Joins needs to get all friendid from friends table for the current userid, and for the corresponding friendid it needs to get username from users tables. I used this query but getting the wrong output.

Code:

SELECT friends.friendid,tbl_users.id,tbl_users.username 
		  FROM friends,tbl_users
		  WHERE tbl_users.id='$userid'

bharanidharanit · #2 (**permalink**) 01-27-10, 04:23

Hi,
This one is working for me. Does the syntax correct for this query?

Code:

SELECT id,username
		  FROM tbl_users
		  WHERE id in (SELECT friendid FROM friends WHERE userid='$userid')

mike_bike_kite · #3 (**permalink**) 01-27-10, 04:53

Quote:

Originally Posted by bharanidharanit

This one is working for me. Does the syntax correct for this query?

If it runs then I guess the syntax is correct however it looks very ugly and will run slowly if you have a lot of data. Better to either use the following or look up the JOIN syntax:
Code:
SELECT id,username
FROM   tbl_users u, friends f
WHERE  u.id = '$userid'
       and f.userid = u.id

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