[摘要]+------------+1 row in set (0.26 sec)mysql> explain (select id from helei order by id) union all...
+------------+
1 row in set (0.26 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