[摘要]+------------+1 row in set (0.00 sec)、mysql> explain (select id from helei order by id) union al...
+------------+
1 row in set (0.00 sec)、
mysql> explain (select id from helei order by id) union all (select id from t where id=0 order by id);
+----+-------------+-------+------------+-------+---------------+--------+---------+------+------+----------+-------------+
关键词：MySQL5.7中union all用法的黑科技的图文代码介绍