计算两个日期之间的工作日

#1 楼

#2 楼

--Changing current database to the Master database allows function to be shared by everyone.
USE MASTER
GO
--If the function already exists, drop it.
IF EXISTS
(
    SELECT *
    FROM dbo.SYSOBJECTS
    WHERE ID = OBJECT_ID(N'[dbo].[fn_WorkDays]')
    AND XType IN (N'FN', N'IF', N'TF')
)
DROP FUNCTION [dbo].[fn_WorkDays]
GO
 CREATE FUNCTION dbo.fn_WorkDays
--Presets
--Define the input parameters (OK if reversed by mistake).
(
    @StartDate DATETIME,
    @EndDate   DATETIME = NULL --@EndDate replaced by @StartDate when DEFAULTed
)

--Define the output data type.
RETURNS INT

AS
--Calculate the RETURN of the function.
BEGIN
    --Declare local variables
    --Temporarily holds @EndDate during date reversal.
    DECLARE @Swap DATETIME

    --If the Start Date is null, return a NULL and exit.
    IF @StartDate IS NULL
        RETURN NULL

    --If the End Date is null, populate with Start Date value so will have two dates (required by DATEDIFF below).
     IF @EndDate IS NULL
        SELECT @EndDate = @StartDate

    --Strip the time element from both dates (just to be safe) by converting to whole days and back to a date.
    --Usually faster than CONVERT.
    --0 is a date (01/01/1900 00:00:00.000)
     SELECT @StartDate = DATEADD(dd,DATEDIFF(dd,0,@StartDate), 0),
            @EndDate   = DATEADD(dd,DATEDIFF(dd,0,@EndDate)  , 0)

    --If the inputs are in the wrong order, reverse them.
     IF @StartDate > @EndDate
        SELECT @Swap      = @EndDate,
               @EndDate   = @StartDate,
               @StartDate = @Swap

    --Calculate and return the number of workdays using the input parameters.
    --This is the meat of the function.
    --This is really just one formula with a couple of parts that are listed on separate lines for documentation purposes.
     RETURN (
        SELECT
        --Start with total number of days including weekends
        (DATEDIFF(dd,@StartDate, @EndDate)+1)
        --Subtact 2 days for each full weekend
        -(DATEDIFF(wk,@StartDate, @EndDate)*2)
        --If StartDate is a Sunday, Subtract 1
        -(CASE WHEN DATENAME(dw, @StartDate) = 'Sunday'
            THEN 1
            ELSE 0
        END)
        --If EndDate is a Saturday, Subtract 1
        -(CASE WHEN DATENAME(dw, @EndDate) = 'Saturday'
            THEN 1
            ELSE 0
        END)
        )
    END
GO

#3 楼

--Changing current database to the Master database allows function to be shared by everyone.
USE MASTER
GO
--If the function already exists, drop it.
IF EXISTS
(
    SELECT *
    FROM dbo.SYSOBJECTS
    WHERE ID = OBJECT_ID(N'[dbo].[fn_WorkDays]')
    AND XType IN (N'FN', N'IF', N'TF')
)

DROP FUNCTION [dbo].[fn_WorkDays]
GO
 CREATE FUNCTION dbo.fn_WorkDays
--Presets
--Define the input parameters (OK if reversed by mistake).
(
    @StartDate DATETIME,
    @EndDate   DATETIME = NULL --@EndDate replaced by @StartDate when DEFAULTed
)

--Define the output data type.
RETURNS INT

AS
--Calculate the RETURN of the function.
BEGIN
    --Declare local variables
    --Temporarily holds @EndDate during date reversal.
    DECLARE @Swap DATETIME

    --If the Start Date is null, return a NULL and exit.
    IF @StartDate IS NULL
        RETURN NULL

    --If the End Date is null, populate with Start Date value so will have two dates (required by DATEDIFF below).
    IF @EndDate IS NULL
        SELECT @EndDate = @StartDate

    --Strip the time element from both dates (just to be safe) by converting to whole days and back to a date.
    --Usually faster than CONVERT.
    --0 is a date (01/01/1900 00:00:00.000)
    SELECT @StartDate = DATEADD(dd,DATEDIFF(dd,0,@StartDate), 0),
            @EndDate   = DATEADD(dd,DATEDIFF(dd,0,@EndDate)  , 0)

    --If the inputs are in the wrong order, reverse them.
    IF @StartDate > @EndDate
        SELECT @Swap      = @EndDate,
               @EndDate   = @StartDate,
               @StartDate = @Swap

    --Calculate and return the number of workdays using the input parameters.
    --This is the meat of the function.
    --This is really just one formula with a couple of parts that are listed on separate lines for documentation purposes.
    RETURN (
        SELECT
        --Start with total number of days including weekends
        (DATEDIFF(dd,@StartDate, @EndDate)+1)
        --Subtact 2 days for each full weekend
        -(DATEDIFF(wk,@StartDate, @EndDate)*2)
        --If StartDate is a Sunday, Subtract 1
        -(CASE WHEN DATENAME(dw, @StartDate) = 'Sunday'
            THEN 1
            ELSE 0
        END)
        --If EndDate is a Saturday, Subtract 1
        -(CASE WHEN DATENAME(dw, @EndDate) = 'Saturday'
            THEN 1
            ELSE 0
        END)
        --Subtract all holidays
        -(Select Count(*) from [DB04\DB04].[Gateway].[dbo].[tblHolidays]
          where  [HolDate] between @StartDate and @EndDate )
        )
    END  
GO
-- Test Script
/*
declare @EndDate datetime= dateadd(m,2,getdate())
print @EndDate
select  [Master].[dbo].[fn_WorkDays] (getdate(), @EndDate)
*/

#4 楼

CREATE FUNCTION [dbo].[fn_GetTotalWorkingDaysUsingLoop]
(@DateFrom DATE,
@DateTo   DATE
)
RETURNS INT
AS
     BEGIN
         DECLARE @TotWorkingDays INT= 0;
         WHILE @DateFrom <= @DateTo
             BEGIN
                 IF DATENAME(WEEKDAY, @DateFrom) IN('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday')
                     BEGIN
                         SET @TotWorkingDays = @TotWorkingDays + 1;
                 END;
                 SET @DateFrom = DATEADD(DAY, 1, @DateFrom);
             END;
         RETURN @TotWorkingDays;
     END;
GO

#5 楼

DATENAME(dw, @StartDate) = 'Sunday'

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE FUNCTION BDATEDIFF
(
    @startdate as DATETIME,
    @enddate as DATETIME
)
RETURNS INT
AS
BEGIN
    DECLARE @res int

SET @res = (DATEDIFF(dd, @startdate, @enddate) + 1)
    -(DATEDIFF(wk, @startdate, @enddate) * 2)
    -(CASE WHEN DATEPART(dw, @startdate) = 1 THEN 1 ELSE 0 END)
    -(CASE WHEN DATEPART(dw, @enddate) = 7 THEN 1 ELSE 0 END)

    RETURN @res
END
GO

#6 楼

 DECLARE @TotalDays INT,@WorkDays INT
 DECLARE @ReducedDayswithEndDate INT
 DECLARE @WeekPart INT
 DECLARE @DatePart INT

 SET @TotalDays= DATEDIFF(day, @StartDate, @EndDate) +1
 SELECT @ReducedDayswithEndDate = CASE DATENAME(weekday, @EndDate)
  WHEN 'Saturday' THEN 1
  WHEN 'Sunday' THEN 2
  ELSE 0 END 
 SET @TotalDays=@TotalDays-@ReducedDayswithEndDate
 SET @WeekPart=@TotalDays/7;
 SET @DatePart=@TotalDays%7;
 SET @WorkDays=(@WeekPart*5)+@DatePart

 RETURN @WorkDays

#7 楼

select @Result = (..CMS's answer..)
if  (@Result < 0)
        select @Result = 0
    RETURN @Result

#8 楼

    CREATE TABLE [dbo].[Holiday](
[Id] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](50) NULL,
[Date] [datetime] NOT NULL)

    CREATE TABLE [dbo].[Plan_Phase](
[Id] [int] IDENTITY(1,1) NOT NULL,
[Id_Plan] [int] NOT NULL,
[Id_Phase] [int] NOT NULL,
[Start_Date] [datetime] NULL,
[End_Date] [datetime] NULL,
[Work_Days] [int] NULL)

SELECT Start_Date, End_Date,
 (DATEDIFF(dd, Start_Date, End_Date) + 1)
-(DATEDIFF(wk, Start_Date, End_Date) * 2)
-(SELECT COUNT(*) From Holiday Where Date  >= Start_Date AND Date <= End_Date)
-(CASE WHEN DATENAME(dw, Start_Date) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, End_Date) = 'Saturday' THEN 1 ELSE 0 END)
-(CASE WHEN (SELECT COUNT(*) From Holiday Where Start_Date  = Date) > 0 THEN 1 ELSE 0 END)
-(CASE WHEN (SELECT COUNT(*) From Holiday Where End_Date  = Date) > 0 THEN 1 ELSE 0 END) AS Work_Days
from Plan_Phase

#9 楼

DECLARE @RAWDAYS INT

   SELECT @RAWDAYS =  DATEDIFF(day, @StartDate, @EndDate )--+1
                    -( 2 * DATEDIFF( week, @StartDate, @EndDate ) )
                    + CASE WHEN DATENAME(dw, @StartDate) = 'Saturday' THEN 1 ELSE 0 END
                    - CASE WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN 1 ELSE 0 END 

   SELECT  @RAWDAYS - COUNT(*) 
     FROM HOLIDAY NumberOfBusinessDays
    WHERE [Holiday_Date] BETWEEN @StartDate+1 AND @EndDate 

#10 楼

SELECT DATEDIFF(day, @StartDate, @EndDate) /* all midnights passed */
     - DATEDIFF(week, @StartDate, @EndDate) /* remove sunday midnights */
     - DATEDIFF(week, DATEADD(day, 1, @StartDate), DATEADD(day, 1, @EndDate)) /* remove saturday midnights */

#11 楼

#12 楼

    DECLARE 
        @StartDate date = '2014-01-01',
        @EndDate date = '2014-01-31'; 
    SELECT 
        COUNT(*) As NumberOfWeekDays
    FROM dbo.Calendar
    WHERE CalendarDate BETWEEN @StartDate AND @EndDate
      AND IsWorkDay = 1;

    DECLARE 
    @StartDate datetime = '2014-01-01',
    @EndDate datetime = '2014-01-31'; 
    SELECT 
    SUM(CASE WHEN DATEPART(dw, DATEADD(dd, Number-1, @StartDate)) BETWEEN 2 AND 6 THEN 1 ELSE 0 END) As NumberOfWeekDays
    FROM dbo.Numbers
    WHERE Number <= DATEDIFF(dd, @StartDate, @EndDate) + 1 -- Number table starts at 1, we want a 0 base

#13 楼

DECLARE @StartDate datetime,@EndDate datetime

select @StartDate='3/2/2010', @EndDate='3/7/2010'

DECLARE @TotalDays INT,@WorkDays INT

DECLARE @ReducedDayswithEndDate INT

DECLARE @WeekPart INT

DECLARE @DatePart INT

SET @TotalDays= DATEDIFF(day, @StartDate, @EndDate) +1

SELECT @ReducedDayswithEndDate = CASE DATENAME(weekday, @EndDate)
    WHEN 'Saturday' THEN 1
    WHEN 'Sunday' THEN 2
    ELSE 0 END

SET @TotalDays=@TotalDays-@ReducedDayswithEndDate

SET @WeekPart=@TotalDays/7;

SET @DatePart=@TotalDays%7;

SET @WorkDays=(@WeekPart*5)+@DatePart

SELECT @WorkDays

#14 楼

CREATE FUNCTION x
(
    @StartDate DATETIME,
    @EndDate DATETIME
)
RETURNS INT
AS
BEGIN
    DECLARE @Teller INT

    SET @StartDate = DATEADD(dd,1,@StartDate)

    SET @Teller = 0
    IF DATEDIFF(dd,@StartDate,@EndDate) <= 0
    BEGIN
        SET @Teller = 0 
    END
    ELSE
    BEGIN
        WHILE
            DATEDIFF(dd,@StartDate,@EndDate) >= 0
        BEGIN
            IF DATEPART(dw,@StartDate) < 6
            BEGIN
                SET @Teller = @Teller + 1
            END
            SET @StartDate = DATEADD(dd,1,@StartDate)
        END
    END
    RETURN @Teller
END

#15 楼

Create FUNCTION [dbo].[fnGetBusinessDays]
(
 @PromiseDate date,
 @ReceivedDate date
)
RETURNS integer
AS
BEGIN
 DECLARE @days integer

 SELECT @days = 
    Case when @PromiseDate > @ReceivedDate Then
        DATEDIFF(d,@PromiseDate,@ReceivedDate) + 
        ABS(DATEDIFF(wk,@PromiseDate,@ReceivedDate)) * 2 +
        CASE 
            WHEN DATENAME(dw, @PromiseDate) <> 'Saturday' AND DATENAME(dw, @ReceivedDate) = 'Saturday' THEN 1 
            WHEN DATENAME(dw, @PromiseDate) = 'Saturday' AND DATENAME(dw, @ReceivedDate) <> 'Saturday' THEN -1 
            ELSE 0
        END +
        (Select COUNT(*) FROM CompanyHolidays 
            WHERE HolidayDate BETWEEN @ReceivedDate AND @PromiseDate 
            AND DATENAME(dw, HolidayDate) <> 'Saturday' AND DATENAME(dw, HolidayDate) <> 'Sunday')
    Else
        DATEDIFF(d,@PromiseDate,@ReceivedDate)  -
        ABS(DATEDIFF(wk,@PromiseDate,@ReceivedDate)) * 2  -
            CASE 
                WHEN DATENAME(dw, @PromiseDate) <> 'Saturday' AND DATENAME(dw, @ReceivedDate) = 'Saturday' THEN 1 
                WHEN DATENAME(dw, @PromiseDate) = 'Saturday' AND DATENAME(dw, @ReceivedDate) <> 'Saturday' THEN -1 
                ELSE 0
            END -
        (Select COUNT(*) FROM CompanyHolidays 
            WHERE HolidayDate BETWEEN @PromiseDate and @ReceivedDate 
            AND DATENAME(dw, HolidayDate) <> 'Saturday' AND DATENAME(dw, HolidayDate) <> 'Sunday')
    End


 RETURN (@days)

END

#16 楼

CREATE TABLE Calendar
(
  dt SMALLDATETIME PRIMARY KEY, 
  IsWorkDay BIT
);

--fill the rows with normal days, weekends and holidays.


create function AddWorkingDays (@initialDate smalldatetime, @numberOfDays int)
    returns smalldatetime as 

    begin
        declare @result smalldatetime
        set @result = 
        (
            select t.dt from
            (
                select dt, ROW_NUMBER() over (order by dt) as daysAhead from calendar 
                where dt > @initialDate
                and IsWorkDay = 1
                ) t
            where t.daysAhead = @numberOfDays
        )

        return @result
    end

#17 楼

DECLARE @StartDate DATETIME
DECLARE @EndDate DATETIME
SET @StartDate = '2018/01/01'
SET @EndDate = '2019/01/01'

SELECT DATEDIFF(Day, @StartDate, @EndDate) -- Total Days
  - (DATEDIFF(Day, 0, @EndDate)/7 - DATEDIFF(Day, 0, @StartDate)/7) -- Sundays
  - (DATEDIFF(Day, -1, @EndDate)/7 - DATEDIFF(Day, -1, @StartDate)/7) -- Saturdays

#18 楼

CREATE FUNCTION [dbo].[fnGetCountWorkingBusinessDays]
(
    @StartDate as DATETIME,
    @EndDate as DATETIME
)
RETURNS INT
AS
BEGIN
    DECLARE @res int

SET @StartDate = CASE 
    WHEN DATENAME(dw, @StartDate) = 'Saturday' THEN DATEADD(dd, 2, DATEDIFF(dd, 0, @StartDate))
    WHEN DATENAME(dw, @StartDate) = 'Sunday' THEN DATEADD(dd, 1, DATEDIFF(dd, 0, @StartDate))
    ELSE @StartDate END

SET @EndDate = CASE 
    WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN DATEADD(dd, 0, DATEDIFF(dd, 0, @EndDate))
    WHEN DATENAME(dw, @EndDate) = 'Sunday' THEN DATEADD(dd, -1, DATEDIFF(dd, 0, @EndDate))
    ELSE @EndDate END


SET @res =
    (DATEDIFF(hour, @StartDate, @EndDate) / 24)
  - (DATEDIFF(wk, @StartDate, @EndDate) * 2)

SET @res = CASE WHEN @res < 0 THEN 0 ELSE @res END

    RETURN @res
END

GO

#19 楼

CREATE FUNCTION dbo.fn_WorkDays(@StartDate DATETIME, @EndDate DATETIME= NULL )
RETURNS INT 
AS
BEGIN
       DECLARE @Days int
       SET @Days = 0

       IF @EndDate = NULL
              SET @EndDate = EOMONTH(@StartDate) --last date of the month

       WHILE DATEDIFF(dd,@StartDate,@EndDate) >= 0
       BEGIN
              IF DATENAME(dw, @StartDate) <> 'Saturday' 
                     and DATENAME(dw, @StartDate) <> 'Sunday' 
                     and Not ((Day(@StartDate) = 1 And Month(@StartDate) = 1)) --New Year's Day.
                     and Not ((Day(@StartDate) = 4 And Month(@StartDate) = 7)) --Independence Day.
              BEGIN
                     SET @Days = @Days + 1
              END

              SET @StartDate = DATEADD(dd,1,@StartDate)
       END

       RETURN  @Days
END

select dbo.fn_WorkDays('1/1/2016', '9/25/2016')

select dbo.fn_WorkDays(StartDate, EndDate) 
from table1

#20 楼

Create Function dbo.DateDiff_WeekDays 
(
@StartDate  DateTime,
@EndDate    DateTime
)
Returns Int
As

Begin   

Declare @Result Int = 0

While   @StartDate <= @EndDate
Begin 
    If DateName(DW, @StartDate) not in ('Saturday','Sunday')
        Begin
            Set @Result = @Result +1
        End
        Set @StartDate = DateAdd(Day, +1, @StartDate)
End

Return @Result

#21 楼

SET DATEFIRST 1
SELECT
,(DATEDIFF(DD,  [StartDate], [EndDate]))        
-(DATEDIFF(wk,  [StartDate], [EndDate]))        
-(DATEDIFF(wk, DATEADD(dd,-@@DATEFIRST,[StartDate]), DATEADD(dd,-@@DATEFIRST,[EndDate]))) AS [WorkingDays] 
FROM /*Your Table*/ 

#22 楼

declare @date1 as datetime = '19900101'
declare @date2 as datetime = '19900120'

select  sum(case when DATENAME(DW,currentDate) not in ('Saturday', 'Sunday') then 1 else 0 end) as noOfWorkDays
from dbo.GetNums(0,DATEDIFF(day,@date1, @date2)-1) as Num
cross apply (select DATEADD(day,n,@date1)) as Dates(currentDate)

#23 楼

CREATE FUNCTION dbo.ufn_CalculateBusinessDays(
@StartDate DATE,
@EndDate DATE = NULL)

RETURNS INT
AS

BEGIN
DECLARE @TotalBusinessDays INT = 0;
DECLARE @TestDate DATE = @StartDate;


IF @EndDate IS NULL
    RETURN NULL;

WHILE @TestDate < @EndDate
BEGIN
    DECLARE @Month INT = DATEPART(MM, @TestDate);
    DECLARE @Day INT = DATEPART(DD, @TestDate);
    DECLARE @DayOfWeek INT = DATEPART(WEEKDAY, @TestDate) - 1; --Monday = 1, Tuesday = 2, etc.
    DECLARE @DayOccurrence INT = (@Day - 1) / 7 + 1; --Nth day of month (3rd Monday, for example)

    --Increment business day counter if not a weekend or holiday
    SELECT @TotalBusinessDays += (
        SELECT CASE
            --Saturday OR Sunday
            WHEN @DayOfWeek IN (6,7) THEN 0
            --New Year's Day
            WHEN @Month = 1 AND @Day = 1 THEN 0
            --MLK Jr. Day
            WHEN @Month = 1 AND @DayOfWeek = 1 AND @DayOccurrence = 3 THEN 0
            --G. Washington's Birthday
            WHEN @Month = 2 AND @DayOfWeek = 1 AND @DayOccurrence = 3 THEN 0
            --Memorial Day
            WHEN @Month = 5 AND @DayOfWeek = 1 AND @Day BETWEEN 25 AND 31 THEN 0
            --Independence Day
            WHEN @Month = 7 AND @Day = 4 THEN 0
            --Labor Day
            WHEN @Month = 9 AND @DayOfWeek = 1 AND @DayOccurrence = 1 THEN 0
            --Columbus Day
            WHEN @Month = 10 AND @DayOfWeek = 1 AND @DayOccurrence = 2 THEN 0
            --Veterans Day
            WHEN @Month = 11 AND @Day = 11 THEN 0
            --Thanksgiving
            WHEN @Month = 11 AND @DayOfWeek = 4 AND @DayOccurrence = 4 THEN 0
            --Christmas
            WHEN @Month = 12 AND @Day = 25 THEN 0
            ELSE 1
            END AS Result);

    SET @TestDate = DATEADD(dd, 1, @TestDate);
END

RETURN @TotalBusinessDays;
END

#24 楼

create FUNCTION [dbo].[ShiftHolidayToWorkday](@date date)
RETURNS date
AS
BEGIN
    IF DATENAME( dw, @Date ) = 'Saturday'
        SET @Date = DATEADD(day, - 1, @Date)

    ELSE IF DATENAME( dw, @Date ) = 'Sunday'
        SET @Date = DATEADD(day, 1, @Date)

    RETURN @date
END
GO

create FUNCTION [dbo].[GetHoliday](@date date)
RETURNS varchar(50)
AS
BEGIN
    declare @s varchar(50)

    SELECT @s = CASE
        WHEN dbo.ShiftHolidayToWorkday(CONVERT(varchar, [Year]  ) + '-01-01') = @date THEN 'New Year'
        WHEN dbo.ShiftHolidayToWorkday(CONVERT(varchar, [Year]+1) + '-01-01') = @date THEN 'New Year'
        WHEN dbo.ShiftHolidayToWorkday(CONVERT(varchar, [Year]  ) + '-07-04') = @date THEN 'Independence Day'
        WHEN dbo.ShiftHolidayToWorkday(CONVERT(varchar, [Year]  ) + '-12-25') = @date THEN 'Christmas Day'
        --WHEN dbo.ShiftHolidayToWorkday(CONVERT(varchar, [Year]) + '-12-31') = @date THEN 'New Years Eve'
        --WHEN dbo.ShiftHolidayToWorkday(CONVERT(varchar, [Year]) + '-11-11') = @date THEN 'Veteran''s Day'

        WHEN [Month] = 1  AND [DayOfMonth] BETWEEN 15 AND 21 AND [DayName] = 'Monday' THEN 'Martin Luther King Day'
        WHEN [Month] = 5  AND [DayOfMonth] >= 25             AND [DayName] = 'Monday' THEN 'Memorial Day'
        WHEN [Month] = 9  AND [DayOfMonth] <= 7              AND [DayName] = 'Monday' THEN 'Labor Day'
        WHEN [Month] = 11 AND [DayOfMonth] BETWEEN 22 AND 28 AND [DayName] = 'Thursday' THEN 'Thanksgiving Day'
        WHEN [Month] = 11 AND [DayOfMonth] BETWEEN 23 AND 29 AND [DayName] = 'Friday' THEN 'Day After Thanksgiving'
        ELSE NULL END
    FROM (
        SELECT
            [Year] = YEAR(@date),
            [Month] = MONTH(@date),
            [DayOfMonth] = DAY(@date),
            [DayName]   = DATENAME(weekday,@date)
    ) c

    RETURN @s
END
GO

create FUNCTION [dbo].GetHolidays(@year int)
RETURNS TABLE 
AS
RETURN (  
    select dt, dbo.GetHoliday(dt) as Holiday
    from (
        select dateadd(day, number, convert(varchar,@year) + '-01-01') dt
        from master..spt_values 
        where type='p' 
        ) d
    where year(dt) = @year and dbo.GetHoliday(dt) is not null
)

create proc UpdateHolidaysTable
as

if not exists(select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'Holidays')
    create table Holidays(dt date primary key clustered, Holiday varchar(50))

declare @year int
set @year = 1990

while @year < year(GetDate()) + 20
begin
    insert into Holidays(dt, Holiday)
    select a.dt, a.Holiday
    from dbo.GetHolidays(@year) a
        left join Holidays b on b.dt = a.dt
    where b.dt is null

    set @year = @year + 1
end

create FUNCTION [dbo].[GetWorkDays](@StartDate DATE = NULL, @EndDate DATE = NULL)
RETURNS INT 
AS
BEGIN
    IF @StartDate IS NULL OR @EndDate IS NULL
        RETURN  0

    IF @StartDate >= @EndDate 
        RETURN  0

    DECLARE @Days int
    SET @Days = 0

    IF year(@StartDate) * 100 + datepart(week, @StartDate) = year(@EndDate) * 100 + datepart(week, @EndDate) 
        --same week
        select @Days = (DATEDIFF(dd, @StartDate, @EndDate))
      - (CASE WHEN DATENAME(dw, @StartDate) = 'Sunday' THEN 1 ELSE 0 END)
      - (CASE WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN 1 ELSE 0 END)
      - (select count(*) from Holidays where dt between @StartDate and @EndDate)
    ELSE
        --diff weeks
        select @Days = (DATEDIFF(dd, @StartDate, @EndDate) + 1)
      - (DATEDIFF(wk, @StartDate, @EndDate) * 2)
      - (CASE WHEN DATENAME(dw, @StartDate) = 'Sunday' THEN 1 ELSE 0 END)
      - (CASE WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN 1 ELSE 0 END)
      - (select count(*) from Holidays where dt between @StartDate and @EndDate)
 
    RETURN  @Days
END