如何计算休假时间？

Question

我有一个TmLeave表，结构如下：

EmployeeID     StartDate     EndDate     LeaveDuration
------------------------------------------------------
0001            20/07/2014    20/07/2014       1
0001            21/07/2014    21/07/2014       1
0001            22/07/2014    22/07/2014       1
0001            24/07/2014    25/07/2014       2
0001            26/07/2014    26/07/2014       1
0001            28/07/2014    30/07/2014       3

我想计算员工连续几天的LeaveDuration值总和，我的结果集应如下所示：

EmployeeID     StartDate     EndDate     LeaveDuration
------------------------------------------------------
0001            20/07/2014    22/07/2014       3
0001            24/07/2014    26/07/2014       3
0001            28/07/2014    30/07/2014       3

Answer 1

请使用CTE检查以下答案：

;With T as (
    select 
        ROW_NUMBER() over(partition by a.EmployeeID order by a.StartDate) RN, 
        *
    From tbl a
)
,T1 as (
    select 
        *, 
        RN CN 
    from T 
    where RN=1

    union all

    select 
        T.*, 
        case when T1.EndDate+1=T.StartDate then CN else T.RN end 
    from T join T1 on T.RN=T1.RN+1
) 
select 
    EmployeeID, 
    MIN(StartDate) StartDate, 
    MAX(EndDate) EndDate, 
    SUM(LeaveDuration) LeaveDuration 
from T1
group by EmployeeID, CN

SQL Fiddle Demo