Hi，大家好！我是白日梦！
今天我要跟你分享的MySQL话题是：“各种各样的登陆DB的方式，总有一种适合你！”
本文是MySQL专题的第 33 篇。
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前置知识
我们想登陆到mysql中前提是肯定需要一个用户名和密码：比如
mysql -uroot -proot
在mysql中用户的信息会存放在 mysql数据库下的 user表中 可以像下面这样查看到所有用户信息
mysql> use mysql
Database changed
mysql> select * from user\G
*************************** 1. row ***************************
Host: localhost
User: root
Select_priv: Y
Insert_priv: Y
Update_priv: Y
Delete_priv: Y
Create_priv: Y
Drop_priv: Y
Reload_priv: Y
Shutdown_priv: Y
Process_priv: Y
File_priv: Y
Grant_priv: Y
References_priv: Y
Index_priv: Y
Alter_priv: Y
Show_db_priv: Y
Super_priv: Y
Create_tmp_table_priv: Y
Lock_tables_priv: Y
Execute_priv: Y
Repl_slave_priv: Y
Repl_client_priv: Y
Create_view_priv: Y
Show_view_priv: Y
Create_routine_priv: Y
Alter_routine_priv: Y
Create_user_priv: Y
Event_priv: Y
Trigger_priv: Y
Create_tablespace_priv: Y
ssl_type:
ssl_cipher:
x509_issuer:
x509_subject:
max_questions: 0
max_updates: 0
max_connections: 0
max_user_connections: 0
plugin: mysql_native_password
authentication_string: *C85A9826269E1AD748DFC3CEC32D040735B27207
password_expired: N
password_last_changed: 2019-11-07 14:39:30
password_lifetime: NULL
account_locked: N
*************************** 2. row ***************************
Host: localhost
User: mysql.session
Select_priv: N
其中有一列叫做HOST，HOST的不同值决定了用户拥有不同的登陆方式：比如：
| 标识符 | 含义 |
|---|---|
| % | 任意ip均等登陆 |
| localhost | 只允许本地登陆 |
| 127.0.0.1 | 只允许本地登陆 |
| sv1 | 主机名为sv1的机器可登录，主机名可以在 etc/hostname中查看 |
| ::1 | 本机可登录 |
所以在登陆前，请确定你的使用的登陆用户的HOST列中有相应的配置
骚气的登陆
在mac上登陆华为云的服务器
MacBook-Pro% ssh 'root'@'139.9.92.123'
root@139.9.92.123's password:
Last failed login: Fri May 29 11:03:42 CST 2020 from 202.85.208.14 on ssh:notty
There was 1 failed login attempt since the last successful login.
Last login: Thu May 28 16:36:32 2020 from 202.85.208.7
Welcome to Huawei Cloud Service
-bash: warning: setlocale: LC_CTYPE: cannot change locale (UTF-8): No such file or directory
[root@139 ~]#
在mac上远程登陆服务器上的mysql
MacBook-Pro% ./mysql -h139.9.92.123 -uroot -reqw123.. -P3306
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2174
Server version: 5.7.29 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
mac登陆本地的mysql
如果你有配置环境变量，或者你的mysql的可执行文件在/etc/bin
中，那你可以在任何目录中使用mysql命令
你可以直接像下面这样登陆：
MacBook-Pro% mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>
如果你没有配置环境变量，系统就不能直接识别mysql命令，需要你进入到mysql安装目录下的bin文件下，找到mysql命令，然后执行登陆的动作
MacBook-Pro% /usr/local/mysql/bin/mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>
也可以用远程登陆的方式登陆本地mysql
MacBook-Pro% mysql -h127.0.0.1 -uroot -proot -P3306
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| assignment |
| cal |
本地登陆
我们可以借助mysql.sock实现本地登陆。
那这个mysql.sock是什么？
看起来我们需要了解一下mysql.sock的作用，因为通过它我们可以实现mysql的本地登陆。
mysql.sock应该是mysql的主机和客户机在同一host（物理服务器）上的时候，使用unix domain socket做为通讯协议的载体，它比tcp快。
通过命令可以查看到mysql.sock的位置。
MacBook-Pro% netstat -ln | grep mysql
64e3f4c55eb824d7 stream 0 0 64e3f4c5614859a7 0 0 0 /tmp/mysql.sock
记下这个 mysql.sock的地址。接下来我们会创建一个配置文件，你找个看着比较顺眼的目录放置这个配置文件。
比如就像下面这样：
MacBook-Pro% sudo mkdir etc
MacBook-Pro% ls -l
total 552
-rw-r--r-- 1 root wheel 275235 Mar 24 01:35 LICENSE
-rw-r--r-- 1 root wheel 587 Mar 24 01:35 README
drwxr-xr-x 40 root wheel 1280 Mar 24 02:45 bin
drwxr-x--- 27 _mysql _mysql 864 May 28 20:44 data
drwxr-xr-x 5 root wheel 160 Mar 24 02:44 docs
drwxr-xr-x 2 root wheel 64 May 29 11:39 etc
drwxr-xr-x 53 root wheel 1696 Mar 24 02:44 include
drwxr-x--- 3 _mysql _mysql 96 May 28 20:44 keyring
drwxr-xr-x 11 root wheel 352 May 13 09:16 lib
drwxr-xr-x 4 root wheel 128 Mar 24 02:44 man
drwxr-xr-x 39 root wheel 1248 Mar 24 02:44 share
drwxr-xr-x 6 root wheel 192 May 28 19:20 support-files
MacBook-Pro% cd etc
MacBook-Pro% sudo touch user.root.cnf
MacBook-Pro% sudo vim user.root.cnf
然后在 user.root.cnf 中添加如下的配置：
[client]
user=root
password=root
socket=/tmp/mysql.sock
好了，现在可以这样实现本地登陆
MacBook-Pro% ../bin/mysql --defaults-extra-file=./user.root.cnf
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>
花里胡哨的本地登陆
有时候，你可能会看到其他大佬登陆mysql时直接使用命令：mysql.local
就骚气十足的本地登陆mysql
他是怎么做到的呢？其实很简单、借助alias+mysql.sock实现：
为我们的登陆mysql的命令添加别名，像下面这样：
MacBook-Pro% alias mysql.local='/usr/local/mysql/bin/mysql --defaults-extra-file=/usr/local/mysql/etc/user.root.cnf'
MacBook-Pro% mysql.local
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>
从此，你也可以骚气登陆mysql
最后：欢迎大家关注白日梦！
下一篇（明天）：跟大家分享如下几个常见的面试题：
1、联表查询join时，到底是大表驱动小表还是小表驱动大表更合理？
2、MySQL有哪些联表查询？
3、一道字节跳动的秋招数据库相关面试题
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