Question

用localhost不能连上mysql，但用127.0.0.1却可以，是什么原因

Answer 1

是权限问题。
mysql> select user,password,host from user;
类似如下：
+-------+-------------------------------------------+-----------------+
| user | password | host |
+-------+-------------------------------------------+-----------------+
| root | | localhost |
| root | | email-admin |
| root | | 127.0.0.1 |
| root | | ::1 |
| | | localhost |
| | | email-admin |
| root | | % |

可以执行， 增加root可以访问的位置权限；

mysql>update user set host='%' where user='root';
mysql>flush privileges;