MySQL 'root'@'localhost'无法登录|Access denied for user ‘root’@’localhost’ (using password: YES)”

今天早上同事说MySQL root账号登录不上了。我试了一下

#mysql -u root -p 

提示”Access denied for user ‘root’@’localhost’ (using password: YES)”

因为年后有同事离职，我第一反应是谁修改了root密码？按照忘记root密码来重置一下密码：

#/etc/init.d/mysql stop 
#mysqld_safe –skip-grant-tables & 
#mysql -uroot -p 

mysql>update mysql.user set password=password(‘mypassword’) where user=’root’; 
mysql>flush privileges; 
mysql>quit

用新密码还是无法登录，提示跟上面一样。换一个非root账号登录，查看一下user表：

mysql> select user,host from user;

+———–+———+
| user | host |
+———–+———+
| root | 127.0.0.1 |
| night | % |
+———–+———+

怀疑默认的localhost没有映射到127.0.0.1？试试#mysql -u root -p xxxx -h 127.0.0.1，果然可以登录。
之前配置数据库的同学没有给’root’@’localhost’和’root’@’ip’授权。
grant all privileges on . to ‘root’@’localhost’ identified by ‘mypassword’ with grant option;
grant all privileges on . to ‘root’@’118.192.91.xxx’ identified by ‘mypassword’ with grant option;

再查询一下用户表：
这里写图片描述
然后#mysql -u root -p xxxx，登录成功！

查了一下mysql -h localhost和mysql -h 127.0.0.1的区别，通过localhost连接到mysql是使用UNIX socket，而通过127.0.0.1连接到mysql是使用TCP/IP。看看状态：
mysql -h localhost > status
Connection id: 639
Current database: mysql
Current user: root@localhost
SSL: Not in use
Current pager: stdout
Using outfile: ”
Using delimiter: ;
Server version: 5.6.15-log Source distribution
Protocol version: 10
Connection: Localhost via UNIX socket

mysql -h 127.0.0.1 > status
Connection id: 640
Current database: mysql
Current user: root@localhost
SSL: Not in use
Current pager: stdout
Using outfile: ”
Using delimiter: ;
Server version: 5.6.15-log Source distribution
Protocol version: 10
Connection: 127.0.0.1 via TCP/IP