数据库计算差异

[王晓彤]

DECLARE @table TABLE
(
	id INT,
	date DATETIME,
	sale FLOAT
)
INSERT INTO @table SELECT 1,'2012-12-01',0 UNION ALL
SELECT 2,'2012-12-02',10 UNION ALL
SELECT 3,'2012-12-03',0 UNION ALL
SELECT 4,'2012-12-04',100 UNION ALL
SELECT 5,'2012-12-05',0 UNION ALL
SELECT 6,'2012-12-06',1000

SELECT * FROM @table
WHERE DAY(date)%2=0

/*
   想要双号的累加，计算差异
   2号 就是金额10
   4号 就是2号加4号的金额110
   6号 就是2号加4号加6号的金额1110
*/

[快溜]

select *, sale=(select sum(sale) from @table where DAY(date)%2=0 and id<=a.id) from (SELECT * FROM @table WHERE DAY(date)%2=0) a

[playwarcraft]

select id,date
,sale=(case when day(date)%2=1 then sale else (select sum(sale) from @table where day(date)%2=0 and date<=A.date) end ) 
from @table as A