更改登錄密碼：

有權限賬號能登錄mysql中：

修改當前用戶密碼

set password=password('redhat');    

有權限賬號不能登錄mysql中：

先停mysql,修改配置文件my.cnf

systemctl stop mariadb  #停止mysql
vim /etc/my.cnf   #更改配置文件

在mysqld下新增一行 skip-grant-tables

[mysqld]
skip-grant-tables

重啟mysql

systemctl start mariadb

mysql 空密碼進入

mysql -uroot

進入mysql庫，查看user表：

use mysql;

select Host,User,Password from mysql.user; 

添加密碼：

grant all on *.* to root@localhost identified by '123456' with grant option; 

mysql5.6版本命令

update mysql.user set password=password('123456') where user='root';
flush privileges; #刷新
exit

mysql5.7版本命令

update user set authentication_string=password('123456') where user='root' and Host='localhost';
flush privileges; #刷新
exit

修改密碼8.0版本

新搭建好的mysql,查看默認密碼，如沒有則單機登錄到mysql

cat /var/log/mysqld.log | grep localhost  

更改密碼為空即‘mima’處無內容，即為免密（亦可設置你習慣的密碼，就不是免密了）

alter user 'root'@'localhost' identified by 'mima';
flush privileges;
exit

改完后：

vim /etc/my.cnf

#skip-grant-tables  #注釋 

重啟mysql服務

systemctl restart mariadb 

mysql登錄不上了

大概率是裝有其他mysql，默認是在/tmp/mysql.sock
報錯信息如下：

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

查找到mysqld.sock 對應位置添加軟連接

ps -ef | grep mysql

rm /var/run/mysqld/mysqld.sock
ln -s /tmp/mysql.sock /var/run/mysqld/mysqld.sock

重啟mysql

service mysqld restart 

本機安裝了5.6后，又安裝了mysql8.0

ubuntu22 發現有多個mysql 導致未找到mysqld.sock

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

進行刪除

dpkg -l | grep mysql
#ii  mysql-client-core-8.0                  8.0.37-0ubuntu0.22.04.3                 amd64        MySQL database core client binaries
apt-get remove mysql-client-core-8.0

重啟mysql恢復

systemctl  status mysql