Question

SELECT card_id from logs
WHERE card_id in ('0001', '0002')
ORDER BY date desc limit 1

此代码首先选择与列表匹配的值，然后选择最后一行。我怎样才能首先从card_id中选择最后一行，看看它是否与列表中的任何值匹配

Answer 1

如果在ORDER之前需要WHERE，则必须将其嵌套在派生表中：

select *
from 
 ( SELECT card_id 
   from logs
   ORDER BY date desc limit 1      -- find the last row first
 ) as dt
WHERE card_id in ('0001', '0002')  -- and then filter

Answer 2

这是一种方法，使用子查询从查询中分别选择最后一条记录，查找card_id的特定值：

SELECT l.card_id
FROM logs l
WHERE l.card_id IN ('0001','0002)
AND l.card_id IN (
SELECT TOP 1 card_id FROM logs ORDER BY [Date] DESC)

我想做＆＃34; ORDER BY＆＃34;之前＆＃34;在哪里＆＃34;在SQL中

2 个答案: