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

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.

Here is another version. If your Scenario requires Saturday to be 1st day of Week and Friday to be last day of Week, the below code will handle that:

  DECLARE @myDate DATE = GETDATE()
  SELECT    @myDate,
    DATENAME(WEEKDAY,@myDate),
    DATEADD(DD,-(CHOOSE(DATEPART(dw, @myDate), 1,2,3,4,5,6,0)),@myDate) AS WeekStartDate,
    DATEADD(DD,7-CHOOSE(DATEPART(dw, @myDate), 2,3,4,5,6,7,1),@myDate) AS WeekEndDate

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

you can also use this:

  SELECT DATEADD(day, DATEDIFF(day, 0, WeddingDate) /7*7, 0) AS weekstart,
         DATEADD(day, DATEDIFF(day, 6, WeddingDate-1) /7*7 + 7, 6) AS WeekEnd