1concat()的作用：
可以实现拼接命令
mysql> select user,host from mysql.user;
+---------------+---------------+
| user | host |
+---------------+---------------+
| root | % |
| tyjs09 | % |
| zhihu | 10.0.0.% |
| root | 106.13.186.56 |
| mysql.session | localhost |
| mysql.sys | localhost |
+---------------+---------------+
6 rows in set (0.01 sec)
mysql> select concat(user,"@",host) from mysql.user;
+-------------------------+
| concat(user,"@",host) |
+-------------------------+
| root@% |
| tyjs09@% |
| zhihu@10.0.0.% |
| root@106.13.186.56 |
| mysql.session@localhost |
| mysql.sys@localhost |
+-------------------------+
6 rows in set (0.00 sec)
mysql>
information_schema.tables+concat()实现命令拼接：
原文：https://www.cnblogs.com/tyjs09/p/14280397.html