will upgrading vb301 to 306 screw up my tables?

[sross]

I have some mysql vb3 tables that hacks added to slightly, is this all going to get wiped out when I upgrade? I am thinking it will only alter the core vb3 stuff if anything? I am close to completing file compare merge of my hacks and need some info about what the upgrade script will do, thanks!!

[Xenon]

if you have manually added tables/field the upgrade won't delete them.
it could just be a problem if you added something, which got added in the upgrade as well, but normally you're on the save side :)