declare 
  v_loc varchar2(50);
  cursor c10 is 
    select a.loc 
    from history a,model b
    where a.unit = b.unit ;
begin
  for x in c10 loop
    select loc into v_loc
    from profile 
    where model = 'MAGI_SW'and loc=x.loc
    if sql%rowcount = 0 then
       insert into profile(id,loc,model) values    (id_seq.nextval,x.loc,'MAGIC_SW');
  end if;
 end loop;
end;

SQL> select 'x' from dept where deptno = 999;

no rows selected

SQL> select max('x') from dept where deptno = 999;

M
-


SQL>

DECLARE 
 ...
BEGIN
  FOR x IN c10 LOOP
     ...
  END LOOP;
EXCEPTION
  WHEN NO_DATA_FOUND THEN 
    ...
END;

DECLARE 
 ...
BEGIN
  FOR x IN c10 LOOP
    BEGIN
      ...
    EXCEPTION
      WHEN NO_DATA_FOUND THEN 
       ...
    END;
  END LOOP;
END;