connect to database error : Access denied for user 'root'@'localhost'

参考链接：　https://www.cnblogs.com/JadenFK3326/p/Ubuntu.html

连接到数据库时，提示如下错误：

 connect to database error : Access denied for user 'root'@'localhost'

解决方法如下：

１、　用管理员密码登录  mysql -udebian-sys-maint -p

　　　管理员密码存储位置：/etc/mysql

　　　hbg@rohens:/etc/mysql$ sudo cat debian.cnf
[sudo] hbg 的密码：
# Automatically generated for Debian scripts. DO NOT TOUCH!
[client]
host     = localhost
user     = debian-sys-maint
password = 5Em08U7izRDbYa5J
socket   = /var/run/mysqld/mysqld.sock
[mysql_upgrade]
host     = localhost
user     = debian-sys-maint
password = 5Em08U7izRDbYa5J
socket   = /var/run/mysqld/mysqld.sock

２、修改密码

　　use mysql

　　update mysql.user set authentication_string=password('新密码') where user='root' and Host ='localhost';

　　update user set plugin="mysql_native_password";

　　flush privileges;

　　quit;

３、重启mysql

       service mysql restart