I have a column called message_id and I would like to stack all of the IDs that match each other under each other.

Basically what I'm doing is as follow:

1. The user inputs a message
2. The message gets assigned an ID.
3. If a another use replies to that same ID it gets put right under it. (like a forum in a way)

I've been reading up on the GROUP clause but I'm not sure if thats what I'm looking for.

Does anyone know on how to group them together? thanks