如何查找每个值的日期之间的总和

Question

表 1

Period  datefrom   dateto      code  id

01/2012 18/12/2011 28/12/2011  A     Emp1
01/2012 11/01/2012 14/01/2012  B     Emp1
02/2012 20/12/2011 25/12/2011  A     Emp2
02/2012 01/02/2012 08/01/2012  B     Emp2 'from and to date is greater than current date.
.....

我想通过系统日期验证获取 datefrom 和 dateto 之间的总和

预期输出

ID     PERIOD   A  B TOTAL

Emp1   01/2012  11 4 15
Emp2   02/2012  6  0 6 

'B 为 0，因为起始日期和截止日期大于当前日期。

如何查询此计算..？

任何建议....

Answer 1

SET DATEFORMAT dmy

SELECT
    ID,
    Period,
    (SELECT ISNULL(SUM(DATEDIFF(DAY,datefrom,dateto) + 1),0)
        FROM Test 
        WHERE DATEDIFF(DAY,datefrom,dateto) > 0 and code = 'A'
        and x.Period = Period and x.id = id)
     as ACode,
    (SELECT ISNULL(SUM(DATEDIFF(DAY,datefrom,dateto) + 1),0)
        FROM Test 
        WHERE DATEDIFF(DAY,datefrom,dateto) > 0 and code = 'B'
        and x.Period = Period and x.id = id)
     as Bcode
FROM TABLENAME x
GROUP BY
    Period,
    ID

添加到日期差异的加一是为了考虑部分天数。