Question

I’m not quite sure how to construct an sql join inorder to find who a specific users “friends” are.

For example I have two table

User Table
u_ID  | u_Name
-------------
1     |  bob
2     |  jill
3     |  jack
4     |  susan

Friends Table
f_ID | u_ID1 | u_ID2
--------------------
1    |   1   |   2
2    |   3   |   1
3    |   4   |   2

I need to find a way of getting all of bobs friends, or all of jills friends, for example.

Friends cannot have duplicate results

I.e. can have a row with either (u_ID1 = 1, u_ID2 = 2) or (u_ID1 = 2, u_ID = 1) but not both, as they are technically the same.

Here is my incorrect query

SELECT u.u_Name
FROM user u
INNER JOIN friends f ON (f.u_ID1 = '1' OR f.u_ID2 = '1')

Thanks in advance

---

Solution

Check Kris Babic reply for solution,

also thank you for everyone elses help

Answer 1

This uses a STRAIGHT join, but should work:

select u.u_Name
from friends f, user u
where (f.u_ID1 = '1' and u.u_ID = f.u_ID2) 
  or (f.u_ID2 = '1' and u.u_ID = f.u_ID1)