for example:
SELECT u.USER_ID,u.USER_DISPLAY_NAME,p.POST_ID,p.POST_SUBJECT,p.POST_POSTER_IP
FROM ubbt_POSTS p, ubbt_USERS u
WHERE u.USER_ID=p.USER_ID
AND p.POST_POSTER_IP LIKE "78.20.1.170"
ORDER BY POST_POSTED_TIME DESC
selects all posts from that IP and orders them by most recent first.
you can play around with the LIKE syntax and do things like (no pun): LIKE "78.20.1.%" (wild card the last byte) or LIKE "78.20.1.17_" (wildcards the last character)
just google 'mysql LIKE syntax' for more possibilities
if you are a geek like me and really want to have more fun (evil grin)
use for example: REGEXP "78.[23]0.1.17[0-9]" and join the whacky world of 'regexes'.. that will match 78.20.1.170-179 and 78.30.1.170-179.. note regex notation in mysql is slightly different that what you might be used to in perl or php or for that matter any other regex engine
Good luck