加入在SQL

Question

我有這個疑問已經：

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

如何使用聯接查詢，從用戶表中添加數據如果prefix_messages我有user_id列？

Thanx！

Answer 1

試試這個：

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 

我假設你只是做子選擇，因爲你要顛倒順序，你得到的前30後？