PROCEDURE error_list (
  p_start IN DATE,
  p_end IN DATE
)
IS
BEGIN
  DBMS_OUTPUT.PUT_LINE('Showing error logs for ' || p_start || ' - ' || p_end);
  DBMS_OUTPUT.PUT_LINE('--------------------------------------------------------------------------');
  FOR rec IN (
    SELECT * FROM ERROR_LOG
    WHERE E_DATE BETWEEN p_start AND p_end
    ORDER BY E_USER ASC, E_DATE DESC
  )
  LOOP
    DBMS_OUTPUT.PUT_LINE('[' || rec.E_DATE || '] ' || rec.E_USER || ' ' || rec.ERROR_CODE || ' ' || rec.ERROR_MESSAGE);
  END LOOP;
  EXCEPTION
    WHEN NO_DATA_FOUND THEN
      DBMS_OUTPUT.PUT_LINE('No error logs.');
      v_error_code := SQLCODE;
      v_error_message := SQLERRM;
      INSERT INTO error_log (e_user, e_date, error_code, error_message)
        VALUES (USER, SYSDATE, v_error_code, v_error_message);
    WHEN e_invalid_datatype THEN
      DBMS_OUTPUT.PUT_LINE('Invalid data type.');
      v_error_code := SQLCODE;
      v_error_message := SQLERRM;
      INSERT INTO error_log (e_user, e_date, error_code, error_message)
        VALUES (USER, SYSDATE, v_error_code, v_error_message);
    WHEN OTHERS THEN
      DBMS_OUTPUT.PUT_LINE('Unexpected error occurred.');
      v_error_code := SQLCODE;
      v_error_message := SQLERRM;
      INSERT INTO error_log (e_user, e_date, error_code, error_message)
        VALUES (USER, SYSDATE, v_error_code, v_error_message);
END error_list;