Get latest entry using GROUP BY

Question

I'm pulling out some conversations from my database. They are being grouped by the user_from column.

As of now, it outputs the oldest message. I want it to show the newest message.

What is the most simple way of doing this?

SELECT *
FROM (`mail`)
JOIN `users` ON `users`.`id` = `mail`.`user_from`
JOIN `users_info` ON `users_info`.`user_id` = `mail`.`user_from`
WHERE `user_to` =  '1'
GROUP BY `user_from`
ORDER BY `mail`.`date` desc

mail table

user table (snippet)

This is the current working code. The SecretAgent sent a message newer than Mail from the agency which it should be showing instead

Answer 1

MySQL is unfortunately very lenient about the contents of the GROUP BY clause, which produces unreliable results unless you include all columns in the GROUP BY. It is never recommended to SELECT * in a join query, but we'll leave that for now. What you need to do is perform a subquery join which gets the most recent message for the user by date, joined against the rest of the columns.

SELECT 
  /* Don't actually do this. Be explicit about columns and assign aliases where their names collide */
  users.*,
  users_info.*,
  mail.*
FROM
  `users`
  JOIN `mail` ON `users`.`id` = `mail`.`user_from`
  JOIN `users_info` ON `users_info`.`user_id` = `mail`.`user_from`
  /* Joined subquery gets most recent message from each user */
  JOIN (
    SELECT  user_from, MAX(date) AS date
    FROM mail
    WHERE user_to = '1'
    GROUP BY user_from
    /* Joined back to the main mail table on user_from and date */
  ) most_recent ON mail.user_from = most_recent.user_from AND mail.date = most_recent.date
  WHERE `user_to` =  '1'

Edit Updated to show all most recent senders rather than only one.