MYSQL登录错误：mysqladmin: connect to server at 'localhost' failed

MYSQL登录错误：mysqladmin: connect to server at 'localhost' failed

1.mysql登录错误

mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: NO)'

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

无法修改密码

用 service mysqld stop 

输入 mysql -uroot -p 回车进入
输入原密码

> use mysql;

> update user set password=PASSWORD("long.com")where user="root";
>  更改密码为 long.com

> flush privileges;   #更新权限

> quit 退出

service mysqld restart
mysql -uroot -p新密码进入

二，忘记本地root的登录密码

解决过程：

1、编辑/etc/my.cnf

在[mysqld] 配置部分添加一行

skip-grant-tables

2、保存后重启mysql

[root@web02 etc]# service mysqld restart
Shutting down MySQL.                                       [  OK  ]
Starting MySQL.                                                   [  OK  ]

3、登录数据库重新设置root密码

[root@web02 ~]# mysql -uroot -p mysql
Enter password:

直接回车进入

执行下列语句

mysql> update user set password=password("mysql") where user='root';
Query OK, 4 rows affected (0.00 sec)
Rows matched: 4  Changed: 4  Warnings: 0

如果执行上一条报错如下:
mysql> update user set password=password("123") where user='root';
ERROR 1054 (42S22): Unknown column 'password' in 'field list'

#错误的原因是 5.7版本下的mysql数据库下已经没有password这个字段了，password字段改成了authentication_string

则改用:
mysql> update mysql.user set authentication_string=password('123') where user='root';
Query OK, 1 row affected, 1 warning (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 1


mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
 

4、删除/etc/my.cnf文件中添加的“skip-grant-tables”行，重启mysql；

用新设的密码就能正常登录了；