MySQL5.7中union all用法的黑科技的图文代码介绍

+----+--------------+------------+-------+---------------+--------+---------+------+------+-----------------+ 3 rows in set (0.00 sec)

可以看出，在MySQL5.6版本中，执行结果如下图所示：

从执行计划来看，是把helei表的查询结果和t表的查询结果合并在了一张临时表里，然后输出给客户端。

union all在MySQL5.7/MariaDB10.1下的表现

Part1:MySQL5.7.15

[root@HE1 ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.7.15-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select version();
+------------+

关键词：MySQL5.7中union all用法的黑科技的图文代码介绍