Hi Eric
Thank you for your response. Sorry for the delay in replying - just migrated my site from test local server to live site. Sadly I cannot get your suggestion to work as it gives the same results each time which is AND.
As I have now got it on a live site you can view it for yourself:
stateoccvisajoin_Results.php
If you need to login use:
username: test
password: test
Thanks Jo