Query-ing multiple tables.

Hello everyone.

I have a database, which contains two tables:
Members:
ID; Firstname; Lastname; Log-in; Password; Base.
Mining:
ID; Type; Level; Coordinates.

Now would I like to get a query that does the following:
A: Look what player is accessing the page to determine his base coords (the player is logg-ed in to the site, so he has a valid session going);
B: Extract the required data (the player can set the criteria trough a form!)
C: Post the extracted data onto the site.

The site it's about:
http://swr.infiniteserve.com/swr2/mi...ost_mining.php

Could someone please advise?
Thanks!

Christiaan

You need to create a key in every table