mysql - 将 IN 语句内的 SELECT 语句中的列用于主查询

Question

这是我的查询:

SELECT id
FROM users
WHERE (id IN (
   SELECT user_id
   FROM messages
   WHERE recipient_id='$my_user_id' ORDER BY time DESC)
  OR id IN (
   SELECT recipient_id
   FROM messages
   WHERE user_id='$my_user_id' ORDER BY time DESC))

我收到消息/向其发送消息的人员列表出现，但它们没有正确排序。我希望新邮件收件人位于顶部，而旧邮件收件人位于底部。我该怎么做？

Answer 1

SELECT u.id 
FROM users u
JOIN messages m on m.recipient_id = u.id 
                or m.user_id = u.id
WHERE u.id = '$my_user_id' 
ORDER BY m.time DESC