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我有这个查询，我知道它不起作用，但我把它保留为伪代码，以帮助解释我在做什么。我正在尝试按过去一周的星期几从预订表中获取“预订”和“销售”总计。因此，Mon1B = 星期一的预订，Mon1S = 星期一的销售额。

SELECT  
   CASE WEEKDAY(b.created)
   WHEN 0 THEN (SELECT COUNT(uuid) as Mon1B, SUM(amount) as Mon1S)
   WHEN 1 THEN (SELECT COUNT(uuid) as Tue1B, SUM(amount) as Tue1S)
   WHEN 2 THEN (SELECT COUNT(uuid) as Wed1B, SUM(amount) as Wed1S)
   WHEN 3 THEN (SELECT COUNT(uuid) as Thu1B, SUM(amount) as Thu1S)
   WHEN 4 THEN (SELECT COUNT(uuid) as Wed1B, SUM(amount) as Wed1S)
   WHEN 5 THEN (SELECT COUNT(uuid) as Wed1B, SUM(amount) as Wed1S)
   WHEN 6 THEN (SELECT COUNT(uuid) as Wed1B, SUM(amount) as Wed1S)
END CASE
FROM Bookings b
WHERE b.created > '#week1Start#' and b.created <= '#week1End#'

如何在 MySQL 中完成这样的事情？

4

3 回答 3

3

是的，但是 case 只能返回一个值。你可以这样做：

SELECT sum(CASE when WEEKDAY(b.created) = 0 then 1 else 0 end) as Mon1b,
       sum(case when weekday(b.created) = 0 then amount else 0 end) as Mon1S,
       ...
FROM Bookings b
WHERE b.created > '#week1Start#' and b.created <= '#week1End#'

不过，您可能会发现 7 行更容易：

select WEEKDAY(b.created), count(*) as cnt, sum(amount) as amt
from Bookings b
WHERE b.created > '#week1Start#' and b.created <= '#week1End#'
group by WEEKDAY(b.created)
order by 1
于 2012-07-26T23:50:59.023 回答
1

我想你想要这样的东西：

SELECT COUNT(IF(WEEKDAY(b.created)=0,uuid,NULL)) AS Mon1B
     , SUM(IF(WEEKDAY(b.created)=0,amount,NULL)) AS Mon1S
     , COUNT(IF(WEEKDAY(b.created)=1,uuid,NULL)) AS Tue1B
     , SUM(IF(WEEKDAY(b.created)=1,amount,NULL)) AS Tue1S

或者，如果您更喜欢等效（但更长）的 CASE 表达式：

SELECT COUNT(CASE WEEKDAY(b.created) WHEN 0 THEN uuid END) AS Mon1B
     , SUM(CASE WEEKDAY(b.created) WHEN 0 THEN amount END) AS Mon1S
     , COUNT(CASE WEEKDAY(b.created) WHEN 1 THEN uuid END) AS Tue1B
     , SUM(CASE WEEKDAY(b.created) WHEN 1 THEN amount END) AS Tue1S

CASE 表达式的结果是一个标量；它不能返回多个值。

于 2012-07-26T23:54:40.190 回答
0 
SELECT  WEEKDAY(b.created),
   CASE 
   WHEN b.weekday='Monday' THEN (SELECT COUNT(b.uuid) as Mon1B, SUM(s.amount) as Mon1S from bookings b,sales s      where b.day='Monday' and s.day='Monday')
   WHEN b.weekday='Tuesday' THEN (SELECT COUNT(b.uuid) as Tue1B, SUM(s.amount) as Tue1 from bookings b,sales s      where b.day='Tuesday' and s.day='tuesday')
   WHEN b.weekday='Wednesday' THEN (SELECT COUNT(b.uuid) as Wed1B, SUM(s.amount) as Wed1S from bookings b,sales s      where b.day='wednesday' and s.day='wednesday')
   WHEN b.weekday='Thursday' THEN (SELECT COUNT(b.uuid) as Thu1B, SUM(s.amount) as Thu1S from bookings b,sales s      where b.day='Thursday' and s.day='Thursday')
   WHEN b.weekday='Friday' THEN (SELECT COUNT(b.uuid) as Fri1B, SUM(s.amount) as Fri1S from bookings b,sales s      where b.day='Friday' and s.day='Friday')
   WHEN b.weekday='saturaday' THEN (SELECT COUNT(b.uuid) as Sat1B, SUM(s.amount) as sat1S from bookings b,sales s      where b.day='Saturaday' and s.day='Saturaday')
   WHEN b.weekday='Sunday' THEN (SELECT COUNT(b.uuid) as sun1B, SUM(s.amount) as sun1S from bookings b,sales s      where b.day='Sunday' and s.day='Sunday')
END CASE
FROM Bookings b
WHERE b.created > '#week1Start#' and b.created <= '#week1End#'
于 2013-03-13T04:26:19.127 回答