• How To Install MySQL on Ubuntu 18.04

1.Installing MySQL

sudo apt update

sudo apt install mysql-server

2.Configuring MySQL

sudo mysql_secure_installation

In order to use a password to connect to MySQL as root, you will need to switch its authentication method from auth_socket to mysql_native_password. To do this, open up the MySQL prompt from your terminal:

sudo mysql

Next, check which authentication method each of your MySQL user accounts use with the following command:

SELECT user,authentication_string,plugin,host FROM mysql.user;

Output
+------------------+-------------------------------------------+-----------------------+-----------+
| user             | authentication_string                     | plugin                | host      |
+------------------+-------------------------------------------+-----------------------+-----------+
| root             |                                           | auth_socket           | localhost |
| mysql.session    | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| mysql.sys        | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| debian-sys-maint | *CC744277A401A7D25BE1CA89AFF17BF607F876FF | mysql_native_password | localhost |
+------------------+-------------------------------------------+-----------------------+-----------+
4 rows in set (0.00 sec)

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';
FLUSH PRIVILEGES;

Check the authentication methods employed by each of your users again to confirm that root no longer authenticates using the auth_socket plugin:

SELECT user,authentication_string,plugin,host FROM mysql.user;

Output
+------------------+-------------------------------------------+-----------------------+-----------+
| user             | authentication_string                     | plugin                | host      |
+------------------+-------------------------------------------+-----------------------+-----------+
| root             | *3636DACC8616D997782ADD0839F92C1571D6D78F | mysql_native_password | localhost |
| mysql.session    | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| mysql.sys        | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| debian-sys-maint | *CC744277A401A7D25BE1CA89AFF17BF607F876FF | mysql_native_password | localhost |
+------------------+-------------------------------------------+-----------------------+-----------+
4 rows in set (0.00 sec)

ทีนี้ก็จะ login ด้วย $ mysql -u root -p ได้ละ

3.Adjusting User Authentication and Privileges

$ mysql -u root -p
mysql> GRANT ALL ON *.* TO 'sammy'@'localhost' IDENTIFIED BY 'password';
mysql> FLUSH PRIVILEGES;

4.Testing MySQL

$ systemctl status mysql.service
● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
   Active: active (running) since Thu 2020-02-06 15:32:25 +07; 17min ago
 Main PID: 3831 (mysqld)
    Tasks: 28 (limit: 4915)
   CGroup: /system.slice/mysql.service
           └─3831 /usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid

ถ้า mysql ไม่ start ให้ start ด้วย

$ sudo systemctl start mysql 

ดูเวอร์ชันของ mysqladmin

$ sudo mysqladmin -p -u root version
Enter password: 
mysqladmin  Ver 8.42 Distrib 5.7.29, for Linux on x86_64
Copyright (c) 2000, 2020, 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.

Server version		5.7.29-0ubuntu0.18.04.1
Protocol version	10
Connection		Localhost via UNIX socket
UNIX socket		/var/run/mysqld/mysqld.sock
Uptime:			18 min 31 sec

Threads: 1  Questions: 21  Slow queries: 0  Opens: 113  Flush tables: 1  Open tables: 106  Queries per second avg: 0.018