选择随机行，并在达到特定的总和/总计时停止

Question

我正在使用SQL Server 2012，并且正在尝试执行以下操作：

SELECT SUM(MILES) from tblName WHERE 
mDate > = '03/01/2012' and 
mDate <= '03/31/2012' 
-- and...
/* 
   now I want to add here do until the SUM of Miles 
   is equal to or greater then '3250' and get the 
   results rows randomly
*/

因此，换句话说，我想从表中选择具有指定的截止日期和日期的随机行，并在里程总和等于或大于该数字时停止：3250

Answer 1

由于您使用的是SQL Server 2012，因此这是一种无需循环的简单方法。

DECLARE @tbl TABLE(mDate DATE, Miles INT)

INSERT @tbl VALUES
('20120201', 520),  ('20120312', 620),
('20120313', 720),  ('20120314', 560),
('20120315', 380),  ('20120316', 990),
('20120317', 1020), ('20120412', 520);

;WITH x AS 
(
 SELECT 
   mDate, 
   Miles, 
   s = SUM(Miles) OVER 
   (
     ORDER BY NEWID() ROWS UNBOUNDED PRECEDING
   )
 FROM @tbl
 WHERE mDate >= '20120301' 
 AND mDate < '20120401'
)
SELECT 
  mDate, 
  Miles, 
  s
FROM x 
WHERE s <= 3250
ORDER BY s;

SQLfiddle演示-多次单击“运行SQL”以查看随机结果。