mysql - 在 SQL 中连接多个查询

Question

我已经有这个查询:

SELECT * FROM (SELECT * FROM `prefix_messages`
                        WHERE `category_id`=4
                        ORDER BY `id` DESC LIMIT 30) ilv
         ORDER BY `id` ASC

如果在 prefix_messages 中我有 user_id 列，如何使用联接查询从用户表中添加数据？

谢谢!

Answer 1

试试这个:

SELECT * FROM   (SELECT pm.ID as prefixID, * FROM prefix_messages as pm
    INNER JOIN users as u
    ON pm.User_id = u.UserId
    WHERE pm.category_id=4
    ORDER BY pm.id DESC LIMIT 30)
    ORDER BY prefixID ASC

我假设您只是进行子选择，因为您想在获得前 30 名后反转顺序？