--工作日处理函数(标准节假日)
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_WorkDay]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_WorkDay]
GO

--计算两个日期相差的工作天数
CREATE FUNCTION f_WorkDay(
@dt_begin datetime,  --计算的开始日期
@dt_end  datetime    --计算的结束日期
)RETURNS int
AS
BEGIN
    DECLARE @workday int,@i int,@bz bit,@dt datetime
    IF @dt_begin>@dt_end
        SELECT @bz=1,@dt=@dt_begin,@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



/*=================================================================*/

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_WorkDayADD]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_WorkDayADD]
GO

--在指定日期上,增加指定工作天数后的日期
CREATE FUNCTION f_WorkDayADD(
@date    datetime,  --基础日期
@workday int       --要增加的工作日数
)RETURNS datetime
AS
BEGIN
    DECLARE @bz int
    --增加整周的天数
    SELECT @bz=CASE WHEN @workday<0 THEN -1 ELSE 1 END
        ,@date=DATEADD(Week,@workday/5,@date)
        ,@workday=@workday%5
    --增加不是整周的工作天数
    WHILE @workday<>0 
        SELECT @date=DATEADD(Day,@bz,@date),
            @workday=CASE WHEN (@@DATEFIRST+DATEPART(Weekday,@date)-1)%7 BETWEEN 1 AND 5
                THEN @workday-@bz ELSE @workday END
    --避免处理后的日期停留在非工作日上
    WHILE (@@DATEFIRST+DATEPART(Weekday,@date)-1)%7 in(0,6) 
        SET @date=DATEADD(Day,@bz,@date)
    RETURN(@date)
END





--工作日处理函数(自定义节假日)

if exists (select * from dbo.sysobjects where id = object_id(N'[tb_Holiday]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [tb_Holiday]
GO

--定义节假日表
CREATE TABLE tb_Holiday(
HDate smalldatetime primary key clustered, --节假日期
Name nvarchar(50) not null)             --假日名称
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_WorkDay]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_WorkDay]
GO

--计算两个日期之间的工作天数
CREATE FUNCTION f_WorkDay(
@dt_begin datetime,  --计算的开始日期
@dt_end  datetime   --计算的结束日期
)RETURNS int
AS
BEGIN
    IF @dt_begin>@dt_end
        RETURN(DATEDIFF(Day,@dt_begin,@dt_end)
            +1-(
                SELECT COUNT(*) FROM tb_Holiday
                WHERE HDate BETWEEN @dt_begin AND @dt_end))
    RETURN(-(DATEDIFF(Day,@dt_end,@dt_begin)
        +1-(
            SELECT COUNT(*) FROM tb_Holiday
            WHERE HDate BETWEEN @dt_end AND @dt_begin)))
END
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_WorkDayADD]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_WorkDayADD]
GO

--在指定日期上增加工作天数
CREATE FUNCTION f_WorkDayADD(
@date    datetime,  --基础日期
@workday int       --要增加的工作日数
)RETURNS datetime
AS
BEGIN
    IF @workday>0
        WHILE @workday>0
            SELECT @date=@date+@workday,@workday=count(*)
            FROM tb_Holiday
            WHERE HDate BETWEEN @date AND @date+@workday
    ELSE
        WHILE @workday<0
            SELECT @date=@date+@workday,@workday=-count(*)
            FROM tb_Holiday
            WHERE HDate BETWEEN @date AND @date+@workday
    RETURN(@date)
END