Using DISTINCT in MySQL only on the right column?

Question

MySQL

Good afternoon.
I ask for help explaining how to correctly query the MySQL database with the DISTINCT parameter.
The fact is that I don’t need all the columns from the table, only those specified by SELECT "th. At the same time, DISTINCT does not work correctly.
SQL:
SELECT ` user `, ` message `, ` date `, ` read `, ` attach `, ` name `
FROM user_dialog d
JOIN user u
ON u.id = d.why
WHERE (d.user = 1)
Actually the question is: how can I change the query so that the result would be with a unique user_dialog.user field?

Answer 1

You need, as I understand it, to group and not to use DISTINCT:

SELECT `user`,`message`,`date`,`read`,`attach`,`name`
FROM user_dialog d
JOIN user u
ON u.id = d.why
WHERE (d.user = 1) 
GROUP BY `user`

Answer 2

If we represent the dialog table in the form: dialog(sender_id, recipient_id, message, date ...), then the query will be something like this:
This query will display all unique pairs of interlocutors.