SQL DATEPART(dw,date) need monday = 1 and sunday = 7

Question

I have a Query where I get the WeekDay of a date but by default:

• Sunday = 1

• Moday = 2

• etc.

Answer 1

I think this could work:

  select
    case when datepart(dw,[Date]) = 1 then 7 else DATEPART(DW,[Date])-1 end as WeekDay

Answer 2

I think

DATEPART(dw,ads.date - 1) as weekday 

would work.

Answer 3

I would suggest that you just write the case statement yourself using datename():

select (case datename(dw, aws.date)
             when 'Monday' then 1
             when 'Tuesday' then 2
             when 'Wednesday' then 3
             when 'Thursday' then 4
             when 'Friday' then 5
             when 'Saturday' then 6
             when 'Sunday' then 7
        end)

At least, this won't change if someone changes the parameter on the day of the week when weeks begin. On the other hand, it is susceptible to the language chosen for SQL Server.

Answer 4

Try this:

CREATE FUNCTION dbo.FnDAYSADDNOWK(
          @addDate AS DATE, 
          @numDays AS INT
       ) RETURNS DATETIME AS

    BEGIN
    WHILE @numDays > 0 BEGIN
        SET @addDate = DATEADD(day, 1, @addDate)    
        IF DATENAME(DW, @addDate) <> 'sunday' BEGIN
            SET @numDays = @numDays - 1 
        END
    END

    RETURN CAST(@addDate AS DATETIME)
END

Answer 5

This will do it.

SET DATEFIRST 1;

-- YOUR QUERY

Examples

-- Sunday is first day of week
set datefirst 7; 
select DATEPART(dw,getdate()) as weekday


-- Monday is first day of week
set datefirst 1;
select DATEPART(dw,getdate()) as weekday

Answer 6

You would need to set DATEFIRST. Take a look at this article. I believe this should help.

https://docs.microsoft.com/en-us/sql/t-sql/statements/set-datefirst-transact-sql