Get the week start date and week end date from week number

I have a query that counts member's wedding dates in the database.

SELECT 
  SUM(NumberOfBrides) AS [Wedding Count]
  , DATEPART( wk, WeddingDate) AS [Week Number]
  , DATEPART( year, WeddingDate) AS [Year]
FROM  MemberWeddingDates
GROUP BY DATEPART(year, WeddingDate), DATEPART(wk, WeddingDate)
ORDER BY SUM(NumberOfBrides) DESC

How do I work out when the start and end of each week represented in the result set?

SELECT
  SUM(NumberOfBrides) AS [Wedding Count]
  , DATEPART(wk, WeddingDate) AS [Week Number]
  , DATEPART(year, WeddingDate) AS [Year]
  , ??? AS WeekStart
  , ??? AS WeekEnd
FROM  MemberWeddingDates
GROUP BY DATEPART(year, WeddingDate), DATEPART(wk, WeddingDate)
ORDER BY SUM(NumberOfBrides) DESC

Solution 1:

You can find the day of week and do a date add on days to get the start and end dates..

DATEADD(dd, -(DATEPART(dw, WeddingDate)-1), WeddingDate) [WeekStart]

DATEADD(dd, 7-(DATEPART(dw, WeddingDate)), WeddingDate) [WeekEnd]

You probably also want to look at stripping off the time from the date as well though.

Solution 2:

Here is a DATEFIRST agnostic solution:

SET DATEFIRST 4     /* or use any other weird value to test it */
DECLARE @d DATETIME

SET @d = GETDATE()

SELECT
  @d ThatDate,
  DATEADD(dd, 0 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Monday,
  DATEADD(dd, 6 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Sunday