mysql installation on ubuntu 18.04

sudo apt update

sudo apt install mysql-server

sudo mysql_secure_installation

sudo mysql, then issue the command: 
SELECT user,authentication_string,plugin,host FROM mysql.user;


Originally, the root user is authenticated with the "auth_socket" plugin.

To configure the root account to authenticate with a password,

run the following ALTER USER command.
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';
 
Replacing the 'password' with a new strong password. 
Note that this command will change the root password you set in Step 2.