https://www.linuxidc.com/Linux/2017-05/143864.htm

进入：mysql -u root -p

Ubuntu18安装5.7

Ubuntu18.04安装mysql5.7

1.1安装

首先执行下面三条命令：

# 安装mysql服务
sudo apt-get install mysql-server
# 安装客户端
sudo apt install mysql-client
# 安装依赖
sudo apt install libmysqlclient-dev
# 检查状态
sudo netstat -tap | grep mysql

1.2设置root密码

mysql5.7安装完成后普通用户不能进mysql，原因：root的plugin被修改成了auth_socket，用密码登陆的plugin应该是mysql_native_password，直接用root权限登录就不用密码,修改root密码和登录验证方式：

$ sudo su
# mysql
mysql>
mysql> select user, plugin from mysql.user;
+------------------+-----------------------+
| user             | plugin                |
+------------------+-----------------------+
| root             | auth_socket           |
| mysql.session    | mysql_native_password |
| mysql.sys        | mysql_native_password |
| debian-sys-maint | mysql_native_password |
+------------------+-----------------------+
4 rows in set (0.00 sec)
mysql> update mysql.user set authentication_string=PASSWORD('123456'), plugin='mysql_native_password' where user='root';
mysql> flush privileges;
mysql> exit
Bye
# exit
$ sudo /etc/init.d/mysql restart
$ mysql -uroot -p

Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.22-0ubuntu18.04.1 (Ubuntu)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> 

1.3配置mysql远程登录

# 修改配置文件，注释掉bind-address = 127.0.0.1
$ sudo vi /etc/mysql/mysql.conf.d/mysqld.cnf

# 保存退出，然后进入mysql服务，执行授权命令：
$ mysql -uroot -p

mysql> grant all on *.* to root@'%' identified by '123456' with grant option;
Query OK, 0 rows affected, 1 warning (0.00 sec)

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

mysql> exit
Bye
$ sudo /etc/init.d/mysql restart

参考：https://blog.csdn.net/lynnyq/article/details/80296137