1 前言

操作mysql的时候发现，有时只建了%的账号，可以通过localhost连接，有时候却不可以，网上搜索也找不到满意的答案，干脆手动测试一波

推荐学习：《mysql视频教程》

2 两种连接方法

这里说的两种连接方法指是执行mysql命令时，%参数填的是localhost还是mysql, 两种连接方式的区别如下

-h 参数为 localhost

当-h参数为localhost的时候，实际上是使用IP连接的（默认连接方式）, 实例如下

[mysql@mysql-test-83 ~]$ /usr/local/mysql57/bin/mysql -utest_user -p -hlocalhost
Enter password: 
========= 省略 ===========

mysql> status
/usr/local/mysql57/bin/mysql  Ver 14.14 Distrib 5.7.21, for linux-glibc2.12 (x86_64) using  EditLine wrapper

Connection id:        9
Current database:    
Current user:        test_user@localhost
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        5.7.21-log MySQL Community Server (GPL)
Protocol version:    10
Connection:        Localhost via UNIX socket

从-h可以看到用户是localhost, 连接方式为socket

-h 参数为 IP

当Current user参数为xx@localhost的时候，实际上是使用Localhost via UNIX socket连接的, 实例如下

[mysql@mysql-test-83 ~]$ /usr/local/mysql57/bin/mysql -utest_user -p -h127.0.0.1
Enter password: 
========= 省略 ===========

mysql> status
--------------
/usr/local/mysql57/bin/mysql  Ver 14.14 Distrib 5.7.21, for linux-glibc2.12 (x86_64) using  EditLine wrapper

Connection id:        11
Current database:    
Current user:        test_user@127.0.0.1
SSL:            Cipher in use is DHE-RSA-AES256-SHA
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        5.7.21-log MySQL Community Server (GPL)
Protocol version:    10
Connection:        127.0.0.1 via TCP/IP
Server characterset:    utf8

从-h可以看到用户是IP, 连接方式为TCP

3 不同版本的差别

测试方法就是看能不能连接，如果不想看测试过程可以拉到最后看结论

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下载

3.1 MySQL 8.0

创建用户

mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.11    |
+-----------+
1 row in set (0.00 sec)

mysql> create user test_user@'%' identified by 'test_user';
Query OK, 0 rows affected (0.07 sec)

使用 localhost 登录

[root@mysql-test-72 ~]# /usr/local/mysql80/bin/mysql -utest_user -p -hlocalhost
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.11 MySQL Community Server - GPL
========= 省略 ===========

mysql> status
--------------
/usr/local/mysql80/bin/mysql  Ver 8.0.11 for linux-glibc2.12 on x86_64 (MySQL Community Server - GPL)

Connection id:        9
Current database:    
Current user:        test_user@localhost
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        8.0.11 MySQL Community Server - GPL
Protocol version:    10
Connection:        Localhost via UNIX socket
...

使用 IP 登录

[root@mysql-test-72 ~]# /usr/local/mysql80/bin/mysql -utest_user -p -h127.0.0.1
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 8.0.11 MySQL Community Server - GPL
========= 省略 ===========

mysql> status
--------------
/usr/local/mysql80/bin/mysql  Ver 8.0.11 for linux-glibc2.12 on x86_64 (MySQL Community Server - GPL)

Connection id:        8
Current database:    
Current user:        test_user@127.0.0.1
SSL:            Cipher in use is DHE-RSA-AES128-GCM-SHA256
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        8.0.11 MySQL Community Server - GPL
Protocol version:    10
Connection:        127.0.0.1 via TCP/IP

结果显示Current user版本的xx@127.0.0.1, TCP/IP 包括8.0

3.2 MySQL 5.7

创建 % 用户

db83-3306>>create user test_user@'%' identified by 'test_user';
Query OK, 0 rows affected (0.00 sec)

使用 localhost 登录

[mysql@mysql-test-83 ~]$ /usr/local/mysql57/bin/mysql -utest_user -p -hlocalhost
========= 省略 ===========

mysql> status
/usr/local/mysql57/bin/mysql  Ver 14.14 Distrib 5.7.21, for linux-glibc2.12 (x86_64) using  EditLine wrapper

Connection id:        9
Current database:    
Current user:        test_user@localhost
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        5.7.21-log MySQL Community Server (GPL)
Protocol version:    10
Connection:        Localhost via UNIX socket
....

使用 IP 登录

[mysql@mysql-test-83 ~]$ /usr/local/mysql57/bin/mysql -utest_user -p -h127.0.0.1
Enter password: 
========= 省略 ===========

mysql> status
--------------
/usr/local/mysql57/bin/mysql  Ver 14.14 Distrib 5.7.21, for linux-glibc2.12 (x86_64) using  EditLine wrapper

Connection id:        11
Current database:    
Current user:        test_user@127.0.0.1
SSL:            Cipher in use is DHE-RSA-AES256-SHA
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        5.7.21-log MySQL Community Server (GPL)
Protocol version:    10
Connection:        127.0.0.1 via TCP/IP
Server characterset:    utf8
...

结果显示MySQL版本的%, localhost 包括5.7

3.3 MySQL 5.6

创建用户

db83-3306>>select version();
+------------+
| version()  |
+------------+
| 5.6.10-log |
+------------+
1 row in set (0.00 sec)

db83-3306>>create user test_user@'%' identified by 'test_user';
Query OK, 0 rows affected (0.00 sec)

使用 localhost 登录

[mysql@mysql-test-83 ~]$ /usr/local/mysql57/bin/mysql -utest_user -p -hlocalhost
Enter password: 
ERROR 1045 (28000): Access denied for user 'test_user'@'localhost' (using password: YES)

使用 IP 登录

[mysql@mysql-test-83 ~]$ /usr/local/mysql57/bin/mysql -utest_user -p -h127.0.0.1
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.6.10-log MySQL Community Server (GPL)
========= 省略 ===========

mysql> status
--------------
/usr/local/mysql57/bin/mysql  Ver 14.14 Distrib 5.7.21, for linux-glibc2.12 (x86_64) using  EditLine wrapper

Connection id:        3
Current database:    
Current user:        test_user@127.0.0.1
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        5.6.10-log MySQL Community Server (GPL)
Protocol version:    10
Connection:        127.0.0.1 via TCP/IP
......
--------------

结果显示MySQL的%不包括localhost

3.4 MySQL 5.1

创建用户

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.1.73    |
+-----------+
1 row in set (0.00 sec)

mysql> create user test_user@'%' identified by 'test_user';
Query OK, 0 rows affected (0.00 sec)

使用 localhost 登录

[root@chengqm ~]# mysql -utest_user -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'test_user'@'localhost' (using password: YES)

使用 IP 登录

[root@chengqm ~]# mysql -utest_user -p -h127.0.0.1
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4901339
Server version: 5.1.73 Source distribution
========= 省略 ===========

mysql> status
--------------
mysql  Ver 14.14 Distrib 5.1.73, for redhat-linux-gnu (x86_64) using readline 5.1

Connection id:        4901339
Current database:    
Current user:        test_user@127.0.0.1
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server version:        5.1.73 Source distribution
Protocol version:    10
Connection:        127.0.0.1 via TCP/IP

结果显示 MySQL 5.6 版本的%不包括localhost

3.5 MariaDB 10.3

创建用户

db83-3306>>select version();
+---------------------+
| version()           |
+---------------------+
| 10.3.11-MariaDB-log |
+---------------------+
1 row in set (0.000 sec)

db83-3306>>create user test_user@'%' identified by 'test_user';
Query OK, 0 rows affected (0.001 sec)

使用 localhost 登录

[mysql@mysql-test-83 ~]$ /usr/local/mariadb/bin/mysql -utest_user -p -hlocalhost
Enter password: 
ERROR 1045 (28000): Access denied for user 'test_user'@'localhost' (using password: YES)

使用 IP 登录

[mysql@mysql-test-83 ~]$ /usr/local/mariadb/bin/mysql -utest_user -p -h127.0.0.1
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 12
Server version: 10.3.11-MariaDB-log MariaDB Server
========= 省略 ===========

MariaDB [(none)]> status
--------------
/usr/local/mariadb/bin/mysql  Ver 15.1 Distrib 10.3.11-MariaDB, for Linux (x86_64) using readline 5.1

Connection id:        12
Current database:    
Current user:        test_user@127.0.0.1
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server:            MariaDB
Server version:        10.3.11-MariaDB-log MariaDB Server
Protocol version:    10
Connection:        127.0.0.1 via TCP/IP

结果显示5.1的%不包括localhost

4 结论