使用mysql -uroot -p,然后输入密码登录mysql时，出现了如下错误：
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
一般这个错误是由密码错误引起，解决的办法自然就是重置密码
解决方案如下：
1.停止mysql数据库：
systemctl stop mysqld
2.用以下命令启动MySQL，以不检查权限的方式启动：
mysqld --skip-grant-tables &
此时又报了一个错误：
2020-01-30T12:56:04.313195Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.19) starting as process 14214 [20:56:04]
2020-01-30T12:56:04.314429Z 0 [ERROR] [MY-010123] [Server] Fatal error: Please read "Security" section of the manual to find out how to run mysqld as root!
2020-01-30T12:56:04.314465Z 0 [ERROR] [MY-010119] [Server] Aborting
2020-01-30T12:56:04.314565Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.19) MySQL Community Server - GPL.
执行命令：
mysqld --user=root --skip-grant-tables &
2020-01-30T12:57:00.762096Z 0 [Warning] [MY-010091] [Server] Can't create test file /var/lib/mysql/mysqld_tmp_file_case_insensitive_test.lower-test [20:57:00]
2020-01-30T12:57:00.762156Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.19) starting as process 14230
2020-01-30T12:57:00.764479Z 0 [Warning] [MY-010091] [Server] Can't create test file /var/lib/mysql/mysqld_tmp_file_case_insensitive_test.lower-test
2020-01-30T12:57:00.764489Z 0 [Warning] [MY-010159] [Server] Setting lower_case_table_names=2 because file system for /var/lib/mysql/ is case insensitive
2020-01-30T12:57:00.764672Z 0 [Warning] [MY-010122] [Server] One can only use the --user switch if running as root
权限不够 +
2020-01-30T12:57:00.764685Z 0 [ERROR] [MY-013276] [Server] Failed to set datadir to '/var/lib/mysql/' (OS errno: 13 - Permission denied)
2020-01-30T12:57:00.764764Z 0 [ERROR] [MY-010119] [Server] Aborting
2020-01-30T12:57:00.764861Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.19) MySQL Community Server - GPL.
[1] + 14230 exit 1 mysqld --user=root --skip-grant-tables
3.登录mysql：mysql -uroot或mysql
4.更新root密码
mysql5.7以下版本：UPDATE mysql.user SET Password=PASSWORD('123456') where USER='root';
mysql8.0版本：UPDATE mysql.user SET authentication_string='123456' WHERE user='root';
5.刷新权限：
flush privileges;
6.退出mysql：exit或quit
7.使用root用户重新登录mysql
mysql -uroot -p
Enter password:<输入新设的密码123456>
来源：oschina
链接：https://my.oschina.net/u/4442894/blog/3162125