Chat as php and ajax in real time [duplicate]

Yes it is possible through AJAX .

For a simple chat version you can make a javascript block that makes an AJAX request to the X database in X seconds through the setTimeout function and gets the conversations only from certain date / time. Whenever you get information added by javascript to the chat window. The php page that receives the request and returns the data must be able to return only the data to a user based on the parameters received.