How to get last week date range based on current date in sql?

Question

I have this code in crystal reports that gives me last week date range based on the current date.

First day of the week:

If DayOfWeek(currentdate) = 2 Then
currentdate
Else If DayOfWeek(currentdate) = 3 Then
dateadd ("d",-1,currentdate)
Else If DayOfWeek(currentdate) = 4 Then
dateadd ("d",-2,currentdate)
Else If DayOfWeek(currentdate) = 5 Then
dateadd ("d",-3,currentdate)
Else If DayOfWeek(currentdate) = 6 Then
dateadd ("d",-4,currentdate)
Else If DayOfWeek(currentdate) = 7 Then
dateadd ("d",-5,currentdate)
Else If DayOfWeek(currentdate) = 1 Then
dateadd ("d",-6,currentdate)

Last day of week:

If DayOfWeek(currentdate) = 2 Then
dateadd ("d",+6,currentdate)
Else If DayOfWeek(currentdate) = 3 Then
dateadd ("d",+5,currentdate)
Else If DayOfWeek(currentdate) = 4 Then
dateadd ("d",+4,currentdate)
Else If DayOfWeek(currentdate) = 5 Then
dateadd ("d",+3,currentdate)
Else If DayOfWeek(currentdate) = 6 Then
dateadd ("d",+2,currentdate)
Else If DayOfWeek(currentdate) = 7 Then
dateadd ("d",+1,currentdate)
Else If DayOfWeek(currentdate) = 1 then currentdate

How can I do the same in SQL using 2 variables to storage Monday(startdate) and Sunday(enddate)?

I found this select datepart(dw,getdate()) --6 in this site, but I do not know how to use it.

Answer 1

I generated some spaced out dates in the parms CTE then SELECT the CurrentDate from parms, the Sunday of the week prior to CurrentDate and the Saturday of the week prior to CurrentDate. I'm assuming that you want the dtate range to be Sunday - Saturday.

Sunday - Saturday Ranges

;WITH parms (CurrentDate) AS (
    SELECT DATEADD(dd, -14, CURRENT_TIMESTAMP) UNION 
    SELECT DATEADD(dd, -6, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 2, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 8, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 15, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 20, CURRENT_TIMESTAMP)
)

SELECT CurrentDate
     , LastWeekSunday   = DATEADD(dd, -1, DATEADD(ww, DATEDIFF(ww, 0, CurrentDate) - 1, 0))
     , LastWeekSaturday = DATEADD(dd,  5, DATEADD(ww, DATEDIFF(ww, 0, CurrentDate) - 1, 0))
FROM parms

Monday to Sunday Ranges

;WITH parms (CurrentDate) AS (
    SELECT DATEADD(dd, -14, CURRENT_TIMESTAMP) UNION 
    SELECT DATEADD(dd, -6, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 2, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 8, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 15, CURRENT_TIMESTAMP) UNION
    SELECT DATEADD(dd, 20, CURRENT_TIMESTAMP)
)

SELECT CurrentDate
     , LastWeekMonday   = DATEADD(dd,  0, DATEADD(ww, DATEDIFF(ww, 0, DATEADD(dd, -1, CurrentDate)) - 1, 0))
     , LastWeekSunday   = DATEADD(dd,  6, DATEADD(ww, DATEDIFF(ww, 0, DATEADD(dd, -1, CurrentDate)) - 1, 0))
FROM parms

If you just want the prior week's Monday to the prior week's Sunday from today rather than from a column of dates you can use this

SELECT CURRENT_TIMESTAMP
     , LastWeekSunday   = DATEADD(dd,  0, DATEADD(ww, DATEDIFF(ww, 0, DATEADD(dd, -1, CURRENT_TIMESTAMP)) - 1, 0))
     , LastWeekSaturday = DATEADD(dd,  6, DATEADD(ww, DATEDIFF(ww, 0, DATEADD(dd, -1, CURRENT_TIMESTAMP)) - 1, 0))