message table

I have a simple table that records messages sent between 2 users like:

+----+------+----+--------+-------+

| id | from | to | msg | date |
+----+------+----+--------+-------+

| 0 | A | B | "msg1" | date1 |
+----+------+----+--------+-------+

| 1 | A | C | "msg2" | date2 |
+----+------+----+--------+-------+

| 2 | C | B | "msg3" | date3 |
+----+------+----+--------+-------+

| 3 | A | B | "msg4" | date4 |
+----+------+----+--------+-------+

| 4 | D | A | "msg5" | date5 |
+----+------+----+--------+-------+

And so on…

My issue is with having almost the same meaning in the fields "from" and "to".

Getting all messages where 'A' is the sender is straightforward but what kind of construction would you advise me to get for example:

• Every distinct user that has communicated one way and/or the other with A?
• And for each distinct one, the last message to or from 'A'?

Thanks for any response/idea/hint! Received on Sat Sep 19 2015 - 08:52:40 CEST