如何在mysqli查詢中應用條件

Question

我想在查詢中應用條件，我想根據條件將一列的值更改為另一列。 請查看我的查詢以及我想要的...

  select user_pro.User_No, user_pro.Fist_Name, user_pro.Last_Name, user_pro.Designation, user_pro.Profile, user_pro.ProfileDP, user_fndrqt.Frnd_SNo, user_fndrqt.Rqst_Sender, user_fndrqt.Rqst_Receiver, user_fndrqt.Rqst_Status from user_pro INNER JOIN user_fndrqt ON user_pro.User_No = user_fndrqt.Rqst_Sender WHERE user_fndrqt.Rqst_Status='1' AND user_fndrqt.Rqst_Sender='$user_id' OR user_fndrqt.Rqst_Receiver='$user_id' ORDER BY Frnd_SNo DESC

在此查詢中，user_pro表包含用戶詳細信息，user_fndrqt包含朋友請求狀態詳細信息$ user_id包含用戶的登錄ID。 現在在這里，我希望如果user_fndrqt.Rqst_Receiver ='$ user_id'，則user_fndrqt.Rqst_Sender值移至user_fndrqt.Rqst_Receiver列。

Answer 1

然后在選擇中為列user_fndrqt.Rqst_Receiver使用IF

IF(user_fndrqt.Rqst_Receiver='$user_id, user_fndrqt.Rqst_Sender,
           user_fndrqt.Rqst_Receiver) as user_fndrqt.Rqst_Receiver