Seasoned (read: old) PHP programmer definitely must have used this MySQL extension most of the time. Build a quick and dirty demo application or proof of concept application, this extension is pretty straightforward. The MySQL extension is the oldest of the three and was the original option developers used to communicate with MySQL. However, this extension is now being deprecated in PHP 5.5 and removed in PHP 7.0. So the choice now is between the other two alternatives because of improvements made in newer releases of both PHP and MySQL and security issues.