DECLARE @counter INT
DECLARE @ilosc int
DECLARE @prodNum varchar(20)
SET @counter = 0
WHILE @counter < 10
   BEGIN
   SET @ilosc = (select FLOOR(RAND()*100))
   SET @prodNum = (select TOP 1 ProduktNumer from Produkt Order by NEWID())
   insert into Sprzedaz values(
      (select TOP 1 KlientId from Klient Order by NEWID()),
      (select @prodNum),
      (select @ilosc),
      ((select @ilosc)*(select TOP 1 Cena from Produkt where ProduktNumer = @prodNum)),
      DEFAULT
   )
   SET @counter = @counter + 1
   END