MySQL：如何获得总和列的最大值？

Question

所以我下面的查询..

select rooms.id room_id, rooms.cnt, booked_dates.cnt, sum(booked_dates.cnt) 
from rooms 
LEFT JOIN booked_dates 
     on rooms.id = booked_dates.rid and 
      (booked_dates.start between '2013-05-06' and '2013-05-09') 
where rooms.ht = 4 and rooms.id = 138 
group by booked_dates.start 

返回以下结果..

现在我需要将它们分组结果由room_id并获得在该max号sum(booked_dates.cnt)列。因此，对于例如将是：

138 | 20 | 4 | 12

我将如何做到这一点？谢谢。

Answer 1

SELECT rooms.id room_id, rooms.cnt, booked_dates.cnt, SUM(booked_dates.cnt) AS booked_sum 
FROM rooms 
LEFT JOIN 
     booked_dates 
ON  rooms.id = booked_dates.rid 
     AND (booked_dates.start between '2013-05-06' and '2013-05-09') 
WHERE rooms.ht = 4 
     AND rooms.id = 138 
GROUP BY 
     booked_dates.start 
ORDER BY 
     booked_sum DESC 
LIMIT 1 

Answer 2

添加MAX（）柱：

select 
    rooms.id room_id, 
    rooms.cnt, 
    booked_dates.cnt, 
    max(booked_dates.cnt) as max , 
    sum(booked_dates.cnt) as sum 
from rooms 
LEFT JOIN booked_dates 
    on rooms.id = booked_dates.rid and 
     (booked_dates.start between '2013-05-06' and '2013-05-09') 
where rooms.ht = 4 and rooms.id = 138 
group by 1, 2, 3 

你有你的组中的错误的条款 - 该查询修复了太（请注意，您可以参考列由他们位置，而不是他们的表达，按分组划分）。