I have a website that has two databases because that is what my hosting account provides. One database has got Classified Ads installed on it. The other has got Jokes and Dating installed on it. That makes it three(3) sections of the website. When a user signs up at one section of the website, he/she doesn't have access to other sections of the website.

I want to make it possible for someone to sign up at one section and still be able to access the other two(2) sections of the website. It appears, apparently, that these there sections are not connected at all.

I have MySql, phpMyAdmin.

I will be very grateful for your response as this has turned out to be a very stressing thing.

you will have more chance if everything was in a single database, that way a linking relationship could be set up between the tables. And the user tables could be integrated.

Alright, most of the data is in a single database, then how should I go about it. How can a linking relationship be set up between the tables? And how can the user tables be integrated?

You need to recode the sign up and login routines to use a single user table OR code the signup routines and user management routines to synchronise the various user tables.

Thank you very much for your assistance. I have already tried to do that. But the problem is that I cant figure out how to do it using phpMyAdmin. It is my favourite tool.

You are not going to accomplish it all with PhpMyAdmin, creating the tables will be ok but you will have to delve into the code of the applications and rewrite parts of it.