CREATE OR REPLACE PROCEDURE TEST0
  (n in number)
  
  IS
  
  BOOL number;

  SELECT MAX(C1) INTO BOOL FROM TEST_DB1;
  
  BEGIN

  IF BOOL = NULL THEN
  FOR i IN 1 .. n LOOP
  INSERT INTO TEST_DB1(C1, C2, C3, C4, C5) VALUES(i, 0, 0, 0, 0);
  END LOOP;
  ELSE
  FOR i IN BOOL .. BOOL+n
  INSERT INTO TEST_DB1(C1, C2, C3, C4, C5) VALUES(i, 0, 0, 0, 0);
  END LOOP;
  END IF;
  
  END;

-------------------

8.3 PLS-00103 심볼 "SELECT"를 만났습니다 다음 중 하나가 기대될 때 : :=. ( @ % ; not null ...

이런오류가 뜨는데 해결법이 뭘까요?