用变量替换函数并在返回值中使用它

Question

我有sql查询，如果2次之间的差异大于1440，那么它将除以7，否则它将返回实际值。问题是我在重复值中重复代码。

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

如何将重复代码替换为这样？

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

Answer 1

您可以尝试使用语句内分配：

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

如果您只想返回一列，请在子查询中包装选择。