计算两个日期之间相差的工作天数

SQL计算两个日期之间相差的工作天数

http://blog.163.com/im_foto/blog/static/49085060200953010553914/ ----计算两个日期之间相差的工作天数
CREATE FUNCTION f_WorkDateDiff(
@dt_begin datetime,
@dt_end datetime)
RETURNS int
AS
BEGIN
    DECLARE @workday int,@i int,@bz bit,@dt datetime
    IF @dt_begin>@dt_end
        SELECT @bz=1,@dt=@dt_bsegin,@dt_begin=@dt_end,@dt_end=@dt
    ELSE
        SET @bz=0
    SELECT @i=DATEDIFF(Day,@dt_begin,@dt_end)+1,
        @workday=@i/7*5,
        @dt_begin=DATEADD(Day,@i/7*7,@dt_begin)
    WHILE @dt_begin<=@dt_end
    BEGIN
        SELECT @workday=CASE
            WHEN (@@DATEFIRST+DATEPART(Weekday,@dt_begin)-1)%7 BETWEEN 1 AND 5
            THEN @workday+1 ELSE @workday END,
            @dt_begin=@dt_begin+1
    END
    RETURN(CASE WHEN @bz=1 THEN -@workday ELSE @workday END)
END
GO

--测试数据
CREATE TABLE tb(Name varchar(10),WorkDate datetime)
INSERT tb SELECT 'aa','2005-01-03'
UNION ALL SELECT 'aa','2005-01-04'
UNION ALL SELECT 'aa','2005-01-05'
UNION ALL SELECT 'aa','2005-01-06'
UNION ALL SELECT 'aa','2005-01-07'
UNION ALL SELECT 'aa','2005-01-10'
UNION ALL SELECT 'aa','2005-01-14'
UNION ALL SELECT 'aa','2005-01-17'
UNION ALL SELECT 'bb','2005-01-11'
UNION ALL SELECT 'bb','2005-01-12'
UNION ALL SELECT 'bb','2005-01-13'
UNION ALL SELECT 'bb','2005-01-10'
UNION ALL SELECT 'bb','2005-01-14'
UNION ALL SELECT 'bb','2005-01-20'
GO

--缺勤统计
DECLARE @dt_begin datetime,@dt_end datetime
SELECT @dt_begin='2005-1-1', --统计的开始日期
    @dt_end='2005-1-20'        --统计的结束日期

--统计
SELECT Name,Days=SUM(Days) FROM(
    SELECT Name,Days=dbo.f_WorkDateDiff(
            DATEADD(Day,1,WorkDate),
            ISNULL(DATEADD(Day,-1,(
                SELECT MIN(WorkDate) FROM tb aa
                WHERE Name=a.Name
                    AND WorkDate>a.WorkDate AND WorkDate<=@dt_end
                    AND NOT EXISTS(
                        SELECT * FROM tb
                        WHERE WorkDate>@dt_begin AND WorkDate<=@dt_end
                            AND Name=aa.Name
                            AND dbo.f_WorkDateDiff(WorkDate,aa.WorkDate)=2))
                ),@dt_end))
    FROM(
        SELECT Name,WorkDate FROM tb
        WHERE WorkDate>=@dt_begin AND WorkDate<@dt_end
        UNION ALL --为每组编号补充查询起始编号是否缺号的辅助记录
        SELECT DISTINCT Name,DATEADD(Day,-1,@dt_begin) FROM tb
    )a
    WHERE (@@DATEFIRST+DATEPART(Weekday,WorkDate)-1)%7 BETWEEN 1 AND 5
        AND NOT EXISTS(
            SELECT * FROM tb
            WHERE WorkDate>@dt_begin AND WorkDate<=@dt_end
                AND Name=a.Name
                AND dbo.f_WorkDateDiff(WorkDate,a.WorkDate)=-2)
)aa GROUP BY Name
/*--结果
Name       Days
---------------- -----------
aa         6
bb         8
--*/