Linking Various Tables

[SithLordKyle]

I was wondering about the feasibility of linking three different tables together.  Normally this is a simple procedure from what I can see, but this is a little more particular maybe.

 

There are three different systems running on our website; a blog system, a content management system, and a gaming system.  Each has it's own table.  Each also has it's own registered users table, the ones we want to link.

 

Basically we want to set it up so if you log into one system, you'll be logged into each system.  All of the tables use a user_id row with the same charset, which I believe may be necessary to pull this off.

 

Any suggestions on coding?

[Wildbug]

Suggestion:  Make a fourth table of your own device, linking together each of the three systems.  Create a login of your own that does whatever is necessary to the tables to define a user as logged in.

[SithLordKyle]

As in running the processes?  There are a few lines of code that would make a user logged in, and I believe it varies through each table.. or at least the amount of rows used.  I assumed if they all had the same rows, named the same, for the username, user_id, and password that would be enough.  Perhaps linked together in php, though I did read something on this before.

 

Any way to clarify that a little bit more? 

[SithLordKyle]

I think I may have misspoken (or mis-typed).  I mean to connect the user tables in three different databases; technically three tables in three databases.  Once logged into one, it also allows access (logged in status) to the other two.

[fenway]

This a common question... the real issue is dealing with the actual php code to "log in", not the DB side.

[SithLordKyle]

Any suggestion on to where to look for an answer to this?  Or perhaps some php coding?