Vypočítejte celkový počet pracovních dnů mezi dvěma daty

Pokud chcete vyloučit pouze víkendy, můžete je jednoduše vyloučit pomocí podmíněného počtu přidáním:

count(distinct case when datepart(weekday, getdate()) <= 5 then date end)

Váš dotaz tedy zní:

set datefirst 1;

select  count(distinct(dateadd(d, 0, datediff(d, 0,checktime)))) as workingdays,
        count(distinct case when datepart(weekday, getdate()) <= 5 
                            then dateadd(d, 0, datediff(d, 0,checktime)) 
                        end) as weekdays
from departments,
 dbo.USERINFO INNER JOIN dbo.CHECKINOUT ON 
     dbo.USERINFO.USERID = dbo.CHECKINOUT.USERID
where  userinfo.name='Gokul Gopalakrishnan' and deptname='GEN/SUP-TBL' 
and checktime>='2014-05-01' and checktime<='2014-05-30'

VŠAK Opravdu bych doporučil přidat kalendářní tabulku do vaší databáze. Díky tomu je vše tak snadné, že váš dotaz bude:

SELECT  DaysWorked = COUNT(cio.Date),
        WeekDaysWorked = COUNT(CASE WHEN c.IsWeekDay = 1 THEN cio.Date END),
        WorkingDaysWorked = COUNT(CASE WHEN c.IsWorkingDay = 1 THEN cio.Date END),
        TotalDays = COUNT(*),
        TotalWeekDays = COUNT(CASE WHEN c.IsWeekDay = 1 THEN 1 END),
        TotalWorkingDays = COUNT(CASE WHEN c.IsWorkingDay = 1 THEN 1 END)
FROM    dbo.Calender AS c
        LEFT JOIN
        (   SELECT  DISTINCT
                    Date = CAST(CheckTime AS DATE)
            FROM    dbo.Departments AS d
                    CROSS JOIN dbo.userInfo AS ui
                    INNER JOIN dbo.CheckInOut AS cio
                        ON cio.UserID = ui.UserID
            WHERE   ui.Name = 'Gokul Gopalakrishnan' 
            AND     d.deptname = 'GEN/SUP-TBL' 
        ) AS cio
            ON c.Date = cio.Date
WHERE   d.Date >= '2014-05-01'
AND     d.Date <= '2014-05-30';

Tímto způsobem můžete definovat státní svátky, víkendy atd. Je to mnohem flexibilnější než jakékoli jiné řešení.

UPRAVIT

Myslím, že jsem špatně pochopil vaše původní kritéria. To by vám mělo fungovat bez tabulky kalendáře:

SET DATEFIRST 1;

DECLARE @StartDate DATE = '2014-05-01', 
        @EndDate DATE = '2014-05-30';

DECLARE @Workdays INT = 
    (DATEDIFF(DAY, @StartDate, @EndDate) + 1)
    -(DATEDIFF(WEEK, @StartDate, @EndDate) * 2)
    -(CASE WHEN DATEPART(WEEKDAY, @StartDate) = 7 THEN 1 ELSE 0 END)
    -(CASE WHEN DATEPART(WEEKDAY, @EndDate) = 6 THEN 1 ELSE 0 END);


SELECT  WorkingDays = COUNT(DISTINCT CAST(CheckTime AS DATE)),
        BusinessDays = @Workdays
FROM    dbo.Departments AS d
        CROSS JOIN dbo.userInfo AS ui
        INNER JOIN dbo.CheckInOut AS cio
            ON cio.UserID = ui.UserID
WHERE   ui.Name = 'Gokul Gopalakrishnan' 
AND     d.deptname = 'GEN/SUP-TBL' 
AND     cio.CheckTime >= @StartDate
AND     cio.CheckTime <= @EndDate;