发布时间：2014-07-17 21:46:49

SELECT_TYPE：1）  SIMPLE：简单的SELECT，不实用UNION或者子查询mysql> explain select * from t2; +----+-------------+-------+------+---------------+------+---------+------+------+-------+| id | select_type | table | type | possible_keys | key &nb.........【阅读全文】