Getting the Starting and ending date in sql

--StartDate and EndDate of Week 
SELECT  DATEADD(DAY, 1 - DATEPART(WEEKDAY, GETDATE()), CAST(GETDATE() AS DATE)) [WeekStart],
        DATEADD(DAY, 7 - DATEPART(WEEKDAY, GETDATE()), CAST(GETDATE() AS DATE)) [WeekEnd]

--StartDay and EndDay of Month
SELECT  DATENAME(WEEKDAY, DATEADD(DAY, 1 - DATEPART(DAY, GETDATE()), GETDATE())) [FirstDayOfMonth],
        DATENAME(WEEKDAY, DATEADD(DAY, - DATEPART(DAY, DATEADD(MONTH, 1, GETDATE())), DATEADD(MONTH, 1, GETDATE()))) [LastDayOfMonth]