Update If Found; Insert If Not Found

Declare
  v_NewMajor  Varchar2(10) := 'Nutrition' ;
  v_LastName  Varchar2(10) := 'Tobias'    ;

Begin
  /*----------------------------*/
  /* Update The Students Table. */
  /*----------------------------*/
  Update Students
     Set Major      = v_NewMajor
   Where Last_Name  = v_LastName  ;

  /*----------------------------------------*/
  /* If not found, then insert this record. */
  /*----------------------------------------*/
    If Sql%Notfound 
  Then Insert Into Students (Id,Last_Name,   Major)
                     Values (Student_Sequence.Nextval, 
                               v_LastName, v_NewMajor);
   End If;
End;
/