mysql - 列出所有发送或接收消息的用户

Question

我有一个表“消息”。

字段是：

- id (primary key, int, auto increment)
- uid (the user who sent the message)
- rid (the user who received the message)
- text (text of the message)
- time (time of message)
- read (read or unread. 0 is unread, 1 is read).

作为用户，我可以是 UID 或 RID。因此，如果我想显示我发送/接收消息的用户列表，我该怎么做？另外，每个用户应该只显示一次。请帮忙。谢谢。:)

Answer 1

一种可能的方法是使用 UNION（不是 UNION ALL），以便删除重复的行：

SELECT uid FROM messages WHERE rid = 'me'
UNION
SELECT rid FROM messages WHERE uid = 'me'

Answer 2

我假设，你的桌子设计看起来像这样，

ID | UID | RID |TEXT |TIME | READ

所以，我相信，根据你的桌子设计，你可以使用这个

SELECT * FROM messages WHERE rid = 'me' OR uid='me'