MYSQl -- Unintall and install

How to uninstall:

sudo apt-get purge mysql-server mysql-client mysql-common mysql-server-core-5.5 mysql-client-core-5.5
sudo rm -rf /etc/mysql /var/lib/mysql
sudo apt-get autoremove
sudo apt-get autoclean

How to install

1.  install the latest version:
   

   
   sudo apt-get update
   
   sudo apt-get install mysql-server
   
   
   

2.  then configure the MySQL:

We'll initialize the MySQL data directory, which is where MySQL stores its data. How you do this depends on which version of MySQL you're running. You can check your version of MySQL with the following command.

mysql --version

You'll see some output like this:

Output

mysql  Ver 14.14 Distrib 5.7.17, for Linux (x86_64) using  EditLine wrapper

 If you're using version 5.7.6 or later, you should use mysqld --initialize instead.

However, if you installed version 5.7 from the Debian distribution, like in step one, the data directory was initialized automatically, so you don't have to do anything.

Regardless of how you installed it, MySQL should have started running automatically. To test this, check its status.

service mysql status

You'll see the following output (with a different PID).

Output

mysql start/running, process 2689

If MySQL isn't running, you can start it with sudo service mysql start.
For an additional check, you can try connecting to the database using the mysqladmin tool, which is a client that lets you run administrative commands. For example, this command says to connect to MySQL as root (-u root), prompt for a password (-p), and return the version.

mysqladmin -p -u root version

You should see output similar to this:

Output

mysqladmin  Ver 8.42 Distrib 5.5.47, for debian-linux-gnu on x86_64
Copyright (c) 2000, 2015, 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      5.5.47-0ubuntu0.14.04.1
Protocol version    10
Connection      Localhost via UNIX socket
UNIX socket     /var/run/mysqld/mysqld.sock
Uptime:         4 min 15 sec

Threads: 1  Questions: 602  Slow queries: 0  Opens: 189  Flush tables: 1 

 Open tables: 41  Queries per second avg: 2.360

This means MySQL is up and running.

You can edit the /etc/mysql/my.cnf file to configure the basic settings -- log file, port number, etc. For example, to configure MySQL to listen for connections from network hosts, change the bind-address directive to the server's IP address:

bind-address            = 192.168.0.5

Replace 192.168.0.5 with the appropriate address.

After making a change to /etc/mysql/mysql.conf.d/mysqld.cnf the MySQL daemon will need to be restarted:

sudo systemctl restart mysql.service

If you would like to change the MySQL root password, in a terminal enter:

sudo dpkg-reconfigure mysql-server-5.5

The MySQL daemon will be stopped, and you will be prompted to enter a new password. 

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket        = /var/run/mysqld/mysqld.sock
port        = 3306
basedir        = /usr
datadir        = /var/lib/mysql
tmpdir        = /tmp
lc-messages-dir    = /usr/share/mysql
skip-external-locking