am asta:

declare @date datetime
set @date = '20080919'

DECLARE @varDayOfWeek INT
SET @varDayOfWeek =((CAST(cast((RTRIM(CONVERT(CHAR(20),@date,101))+' 12:00:00.000') as DATETIME) as INT)%7))

IF (@varDayOfWeek=0 OR @varDayOfWeek=6)
SELECT 'Nu se poate procesa'
ELSE
SELECT dateadd(day,-1,@date) oZiInUrma, dateadd(day,-2,@date) douaZileInUrma

dar cum fac daca oZiInUrma sau douaZileInUrma sa mearga in urma la ziua lucratoare

alex.