Calculate business hours between two dates

Question

How can I calculate business hours between two dates? For example we have two dates; 01/01/2010 15:00 and 04/01/2010 12:00 And we have working hours 09:00 to 17:00 in weekda

Answer 1

ALTER FUNCTION WorkTime_fn (@StartDate DATETIME, @FinishDate DATETIME)
RETURNS VARCHAR(9)
AS
BEGIN
    DECLARE @Temp BIGINT
    SET @Temp=0

    DECLARE @FirstDay VARCHAR(9)
    SET @FirstDay = CONVERT(VARCHAR(9),@StartDate, 112)

    DECLARE @LastDay VARCHAR(9)
    SET @LastDay = CONVERT(VARCHAR(9),@FinishDate, 112)

    DECLARE @StartTime VARCHAR(9)
    SET @StartTime = CONVERT(VARCHAR(9),@StartDate, 108)

    DECLARE @FinishTime VARCHAR(9)
    SET @FinishTime = CONVERT(VARCHAR(9),@FinishDate, 108)

    DECLARE @WorkStart VARCHAR(9)
    SET @WorkStart = '09:30:00'

    DECLARE @WorkFinish VARCHAR(9)
    SET @WorkFinish = '17:30:00'

    IF (@StartTime<@WorkStart)
    BEGIN
        SET @StartTime = @WorkStart
    END
    IF (@FinishTime>@WorkFinish)
    BEGIN
        SET @FinishTime=@WorkFinish
    END

DECLARE @CurrentDate VARCHAR(9)
    SET @CurrentDate = CONVERT(VARCHAR(9),@StartDate, 112)
    DECLARE @LastDate VARCHAR(9)
    SET @LastDate = CONVERT(VARCHAR(9),@FinishDate, 112)

WHILE(@CurrentDate<=@LastDate)
BEGIN       

        IF (DATEPART(dw, @CurrentDate)!=1 AND DATEPART(dw, @CurrentDate)!=7)
        BEGIN
              IF (@CurrentDate!=@FirstDay) AND (@CurrentDate!=@LastDay)
              BEGIN
                   SET @Temp = (@Temp + (8*60))

              END

              ELSE IF (@CurrentDate=@FirstDay) AND (@CurrentDate!=@LastDay)
              BEGIN
                SET @Temp = @Temp + DATEDIFF(MINUTE, @StartTime, @WorkFinish)

              END

              ELSE IF (@CurrentDate!=@FirstDay) AND (@CurrentDate=@LastDay)
              BEGIN
                SET @Temp = @Temp + DATEDIFF(MINUTE, @WorkStart, @FinishTime)

              END

              ELSE IF (@CurrentDate=@FirstDay) AND (@CurrentDate=@LastDay)
              BEGIN
                SET @Temp = DATEDIFF(MINUTE, @StartTime, @FinishTime)

              END

             END

SET @CurrentDate = CONVERT(VARCHAR(9),DATEADD(day, 1, @CurrentDate),112)

END
        Return @TEMP

END