Ubuntu 18.04 安装 mysql 的过程中，竟然没有让你输入秘密？！（之前在 Ubuntu 14.04 下，安装过程中会询问密码），这导致安装完 mysql 初始秘密不知道的问题。
$ sudo apt-get install mysql-server-5.7
解决方法如下：
1）安装完成后，会生成文件 /etc/mysql/debian.cnf ，初始用户名和秘密如下 (这里密码是随机的)
$ sudo cat /etc/mysql/debian.cnf
# Automatically generated for Debian scripts. DO NOT TOUCH!
[client]
host = localhost
user = debian-sys-maint
password = 63vIY3PtyKh10cmZ
socket = /var/run/mysqld/mysqld.sock
[mysql_upgrade]
host = localhost
user = debian-sys-maint
password = 63vIY3PtyKh10cmZ
socket = /var/run/mysqld/mysqld.sock
2）使用这个用户名和秘密登陆 mysql
$ mysql -h 127.0.0.1 -u debian-sys-maint -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.26-0ubuntu0.18.04.1 (Ubuntu) Copyright (c) 2000, 2019, 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>
3）然后做如下操作（这里设置秘密为 1，读者请自行设置自己的密码）
mysql> update mysql.user set authentication_string=password('1') where user='root' and host='localhost';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 1
mysql> update user set plugin='mysql_native_password';
Query OK, 1 row affected (0.00 sec)
Rows matched: 4 Changed: 1 Warnings: 0
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> quit;
Bye
4）重新启动 mysql
$ sudo service mysql restart
5）之后就可以使用 root 登陆了
$ mysql -h 127.0.0.1 -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.26-0ubuntu0.18.04.1 (Ubuntu) Copyright (c) 2000, 2019, 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>
6）检查默认字符编码
mysql> show variables like 'character_set_%';
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.00 sec)
将其改为 utf8，打开 /etc/mysql/mysql.conf.d/mysqld.cnf，在最后添加一句，
character-set-server=utf8
重新启动 mysql，
$ sudo service mysql restart
再次查看字符编码，
mysql> show variables like 'character_set_%';
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.01 sec)
7）使用 mycli 自动补全
默认 mysql 命令行登陆后，输入命令不会提示及自动补全，非常麻烦，通过使用 mycli 自动补全会方便很多。
安装如下，
$ sudo pip install -i https://pypi.tuna.tsinghua.edu.cn/simple/ mycli
使用 mycli 启动数据库连接，
$ mycli -h 127.0.0.1 -u root -p ******** ( here your DB password)
8) 安装 mysql 的 python 借口 mysqlclient (Django 对此接口的支持比 mysql-connector-python 好)
$ sudo apt-get install default-libmysqlclient-dev
$ sudo pip3 install -i https://pypi.tuna.tsinghua.edu.cn/simple/ mysqlclient
本文参考网友博客：https://blog.csdn.net/qq_38737992/article/details/81090373