MySQL column data returned as comma delimited list

Question

I currently have a MySQL table like: ``` id | friend 1 | 2 1 | 5 1 | 10 3 | 6 15 | 19 21 | 4 ``` I'm trying to grab all the friend id's of one particular user and arrange them into a comma-delimited list. For example, grabbed user1's friends, it would return as ``` $friend_list = 2,5,10 ``` Currently, I have: ``` $sql = "SELECT friend FROM table__friends WHERE id = ".$user_id; ``` This only grabs one row though..please help! Thanks

Accepted Answer

You want to use GROUP_CONCAT :

```
$sql = "SELECT GROUP_CONCAT(friend) FROM table__friends GROUP BY id HAVING id = ".$user_id;
```

Adjusted for correctness per the better answer.

MySQL column data returned as comma delimited list

Solution

Problem