SET @seri=:seri;
SET @klasor=:gnc9;
SET @yol=:gnc78;
INSERT INTO okuma
 SELECT seri,klasor,yol FROM (SELECT @seri AS seri, @klasor AS klasor, @yol AS yol )
  WHERE NOT EXISTS (SELECT seri, klasor FROM okuma WHERE seri=@seri AND klasor=@klasor)