selecting all rows where a column has an specific ID

Question

So I have a badly designed database (I think) which I can't change. It's a twitter like app where the users can follow each other. Every user has it`s row in the table, and in that table there is a column named 'following' which represents all USERID's that a user is following. In that column there is a list of USERID's separated with a coma. So lets say the user with the ID 1 is following users 2 and 3 and the user with ID 2 is following user 1 the table would look like this, user 3 is not following anybody.

USERID  |  username         |  following  
-------------------------------------------
1       |  some user        |  2,3                
2       |  test1            |  1                
3       |  test2            |         

Question is how do I show all the users which user 1 is following?

EDIT 1

The code that did not work from 491243, posting here, maybe I missed something in php

$USERID = $_GET['userid'];//this has a value, so not the problem here
$sql_select = "SELECT B.USERID FROM users A INNER JOIN users B ON FIND_IN_SET(B.USERID, B.following) > 0 WHERE B.USERID = '$USERID'";
$result_select = mysqli_query($link,$sql_select);
while($record = mysqli_fetch_array($result_select))
{
    $following = $record['USERID'];
    var_dump($following); //result is nothing, not even NULL
}

EDIT 2 Just for sanity check I did this:

 $sql_select = "SELECT USERID FROM users WHERE USERID = '1'";
 $result_select = mysqli_query($link,$sql_select);
 while($record = mysqli_fetch_array($result_select))
 {
    $following = $record['USERID'];
    var_dump($following); //result is 1, like it`s supposed to be
 }

Is it possible my PHP code is wrong for the query in the replays?

Answer 1

You might be looking for FIND_IN_SET()

SELECT  userid, username
FROM    tableName
WHERE FIND_IN_SET('1', following);

SAMPLE FIDDLE

Answer 2

Your table schema is in bad shape. you should normalize it properly. But to answer you question, you can still get the result you want using JOIN and FIND_IN_SET

SELECT  b.userid, b.username
FROM    tableName a
        INNER JOIN tableName b
            ON FIND_IN_SET(b.userID, a.following) > 0
WHERE   a.userID = 1

• SQLFiddle Demo

My preferred design would be

User Table

• UserID (PK)
• UserName

Following Table

• UserID (FK) - also a PK with FollowID
• FollowID (FK)