Считать рабочие дни между двумя датами

В Вычисление Рабочих дней можно найти хорошую статью об этом предмете, но как Вы видите не то, чтобы усовершенствованный.

--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

, Если необходимо использовать пользовательский календарь, Вы, возможно, должны были бы добавить некоторые проверки и некоторые параметры. Надо надеяться, это обеспечит хорошую начальную точку.

Я одолжил некоторые идеи от других создать мое решение. Я использую встроенный код для игнорирования выходных и американских федеральных праздников. В моей среде EndDate может быть пустым, но он никогда не будет предшествовать StartDate.

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

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

 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