CREATE TRIGGER Trig1
   AFTER INSERT ON Highschooler
when new.grade < 9 or new.grade > 12
begin
   UPDATE Highschooler
set grade = null
where ID= new.ID;
end;

 |

 CREATE TRIGGER Trig2
   AFTER INSERT ON Highschooler
when new.grade = null
begin
  UPDATE Highschooler
set grade = 9
where ID = new.ID;
    end;