I'm confused, which is the best language, that can be used even for database connection, php, Ajax, or Angular Js

Answer 1

You mix a lot of things. Php is a server side language while Ajax is a protocol and Angular JS a JS framework. To access to a database, you need to use a server side language, here php. Then you can do request with your JS framework (Angular JS) to a php page through Ajax.

Answer 2

AngularJS is a framework based on JavaScript and AJAX particularly. AJAX just a technology allows to send requests and receive responses asynchronously (means without waiting).
Asynchronous
JavaScript
And
XML

Answer 3

PHP is best for connection