Manjaro 版本：20.0.3 Lysia
MySQL 版本：8.0.21
安装MySQL
引用自 manjaro安装mysql
sudo su
sudo pacman -S mysql
# 初始化MySQL，记住输出的root密码
mysqld --initialize --user=mysql --basedir=/usr --datadir=/var/lib/mysql
# 设置开机启动MySQL服务
systemctl enable mysqld.service
systemctl daemon-reload
systemctl start mysqld.service
# 使用MySQL前必须修改root密码，MySQL 8.0.15不能使用set password修改密码
mysql -u root -p
mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '新密码';
# 完成
遇到的问题
在初始化 MySQL 时出现以下错误
2020-07-31T11:23:19.936582Z 0 [Warning] [MY-010915] [Server] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release.
2020-07-31T11:23:19.936658Z 0 [System] [MY-013169] [Server] /usr/bin/mysqld (mysqld 8.0.21) initializing of server in progress as process 13951
2020-07-31T11:23:19.938797Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.
2020-07-31T11:23:19.938809Z 0 [ERROR] [MY-013236] [Server] The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.
2020-07-31T11:23:19.938903Z 0 [ERROR] [MY-010119] [Server] Aborting
2020-07-31T11:23:19.939025Z 0 [System] [MY-010910] [Server] /usr/bin/mysqld: Shutdown complete (mysqld 8.0.21) Source distribution.
然后参考这篇文章： Manjaro中MySQL 8 的安装 – Gnome桌面
解决了问题，如下：
上面的主要 [Error] 信息为：
The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.
需要我们删除 /'var/lib/mysql/ 文件夹下的所有文件，输入如下命令，先删除所有文件夹，然后删除所有文件：
rm -rf /var/lib/mysql/*
cd /var/lib/
rm -rf mysql/*
再次初始化
mysqld --initialize --user=mysql --basedir=/usr --datadir=/var/lib/mysql
输出如下日志
2020-07-31T11:27:33.047730Z 0 [Warning] [MY-010915] [Server] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release.
2020-07-31T11:27:33.047842Z 0 [System] [MY-013169] [Server] /usr/bin/mysqld (mysqld 8.0.21) initializing of server in progress as process 14406
2020-07-31T11:27:33.057992Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2020-07-31T11:27:39.916904Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2020-07-31T11:27:46.729463Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: =_QFeBK:!8fw
可以看到第五行有初始化的密码，我的是： =_QFeBK:!8fw
然后设置开机启动 MySQL 服务
# 设置开机启动MySQL服务
systemctl enable mysqld.service
systemctl daemon-reload
systemctl start mysqld.service
进入 MySQL，如下下面一行命令后，输入密码
mysql -u root -p
MySQL 中修改默认密码，我将密码修改为 Admin123
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'Admin123';
OK，完成。