今天把数据库配置文件修改了，结果重启不了了
需要使用 mysqld --initialize 或 mysqld --initialize-insecure 命令来初始化数据库
1、mysqld --initialize-insecure可以不生成随机密码，设置数据库空密码。
2、安装Mysql时默认使用的是mysqld --initialize命令。这个命令也会生成一个随机密码。改密码保存在了Mysql的日志文件中
3、通过配置文件查看日志文件路径 /etc/mysql/mysql.conf.d/mysqld.cnf。打开该文件，可以看到mysql的datadir和log文件等的配置信息
# 日志文件路径 log-error = /var/log/mysql/error.log
4、打开log文件并搜索 password ，可以看到密码
5、登录数据库
使用找到的随机密码登录mysql，首次登录后，mysql要比必须修改默认密码，否则不能执行任何其他数据库操作，这样体现了不断增强的Mysql安全性。
这里会有几个问题
1、提示必须的修改密码
2、8.0修改密码命令
ALTER user 'root'@'localhost' IDENTIFIED BY 'Tinywan123456'
创建新用户
MySQL8.0取消了直接grant创建用户的语法，只能先create user再grant，因此创建root如下
mysql> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> create user user001@'localhost' identified by '112233';
Query OK, 0 rows affected (0.01 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
mysql> create user user002@'%' identified by '112233';
Query OK, 0 rows affected (0.01 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)测试user001远程登录
$ mysql -u user001 -p112233 -h 159.11.213.20
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 35
Server version: 8.0.12 MySQL Community Server - GPL
Copyright (c) 2000, 2018, 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 |
+--------------------+
1 row in set (0.00 sec)
mysql>
Navicat Premium 远程连接不了
提示一下信息
如何解决：
1、先通过命令行进入mysql的root账户
mysql -h localhost -uroot -pTinywan123456
2、更改加密方式
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'password' PASSWORD EXPIRE NEVER;
Query OK, 0 rows affected (0.10 sec)
3、修改密码
mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';
Query OK, 0 rows affected (0.35 sec)
4、清除缓存
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.28 sec)
5、重新连接Navicat Premium 可以正常连接成功
参考：
1、https://www.jb51.net/article/140282.htm
2、https://www.jb51.net/article/47727.htm
3、https://blog.csdn.net/zonghua521/article/details/78198052
4、https://blog.csdn.net/tr1912/article/details/81271851