In this tutorial we are going to build Live Username Availability Check using PHP, JQuery and AJAX. This is a most common and popular feature in most of the website. Mostly this feature is integrated in Login and Registration page.

In the Registration page, When user entered the desire username in username text field and just after that AJAX call will send the request to PHP page to get the availability status of username in MySQL database. The PHP page find the exact match in the database and returns the result message based on the username availability.
Our Script returns the below message based on username availability :
When Username availability match found in database, it will return message "Username is available".
When Username availability match not found in database, it will return message "Username is not available".

For More details :
http://www.skptricks.com/2017/11/live-username-availability-check-using-php-jquery-ajax.html