mysql single query for two tables

how can i combine the following into one query.
the two tables are unrelated lists of IP addresses, one a whitelist and one a blacklist of IP addresses.   I want to to return nothing IF the IP address  IS ANYWHERE in the whitelist
Thus whitelist takes precedence in the logic, over the blacklist.

SELECT blacklist.* FROM blacklist, whitelist  
         WHERE   blacklist.IPaddress='$IPaddress'
             BUT NULL RESULTS     IF     COUNT(whitelist.IPaddress='$IPaddress')>0

i need to do this within one query due to the way i'm executing it via a single shell command.

thanks
willsherwoodAsked:
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Dan CraciunIT ConsultantCommented:
What's wrong with And?
SELECT blacklist.* FROM blacklist, whitelist  
         WHERE   blacklist.IPaddress='$IPaddress' AND COUNT(whitelist.IPaddress='$IPaddress')=0

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HTH,
Dan
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willsherwoodAuthor Commented:
i guess nothing's wrong with "thank you" too
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Dan CraciunIT ConsultantCommented:
Glad I could help!
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willsherwoodAuthor Commented:
please help further - it turns out the COUNT cannot be used in a WHERE clause
"illegal use of GROUP function"

back to original question:   how to include two tables as desired above?
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MySQL Server

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