用變量替換函數並在返回值中使用

Question

我有sql查詢，其中如果2次之差大於1440，那麼它將除以7，否則它將返回實際值。問題是我正在重複返回值中的代碼。

SELECT 
'IF(TIMESTAMPDIFF(MINUTE, now(), end_at) > 1440, TIMESTAMPDIFF(MINUTE, now(), end_at)/ 7, TIMESTAMPDIFF(MINUTE, now(), end_at)) as minutesLeft' 
FROM table 

如何將重複代碼替換爲這樣的代碼？

SELECT 
'IF(TIMESTAMPDIFF(MINUTE, now(), end_at) > 1440, timestamp/7, timestamp) as minutesLeft' 
FROM table 

Answer 1

您可以嘗試使用的語句分配：

set @diff = null; 
SELECT @diff := TIMESTAMPDIFF(MINUTE, now(), end_at), 
IF(@diff > 1440, @diff/7, @diff) as minutesLeft 
FROM table 

裹選擇在一個子查詢，如果你只是想一列返回。