CREATE TABLE test_id (
    ID int,
    PRIMARY KEY (`ID`)
  )
  SELECT * FROM test_id WHERE id=1;

  fix explain NULL able column bug

  +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+--------------------------------+
  | id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra                          |
  +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+--------------------------------+
  |  1 | SIMPLE      | NULL  | NULL       | NULL | NULL          | NULL | NULL    | NULL | NULL |     NULL | no matching row in const table |
  +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+--------------------------------+