Question

In my thread based messaging system, the table schema is

> messages table
id(int auto incr primary key)
body(varchar)
time(datetime)

>message_reference table
id(int auto incr primary key)
message_id(forgain key from message table)
sender
receiver

Here, I want to select the first message id which is sent to a new receiver and sender is the user who is logged in.

Doing this with multiple queries and some code is obviously possible but can it be done with a single query for performance issues??

Answer 1

You can try

EDIT:

If the id is auto increment, then the id will also increase with time and you can use:

SELECT message_reference.message_id, message_reference.receiver, messages.body
FROM message_reference, messages
WHERE message_reference.message_id IN (SELECT  MIN(message_reference.message_id)
                            FROM message_reference
                            GROUP BY message_reference.receiver)
AND message_reference.message_id = messages.id AND message_reference.sender = <sender>