Función día de la semana

Create FUNCTION DayOfWeek
(
@Date as Datetime
)

Returns varchar (30)
AS
BEGIN

Declare @Return varchar (30)

Select @Return=case datepart(dw,@Date)
When 1 Then 'Sunday'
When 2 Then 'Monday'
When 3 Then 'Tuesday'
When 4 Then 'Wednesday'
When 5 Then 'Thursday'
When 6 Then 'Friday'
When 7 Then 'Saturday' End

Return @Return
END