What is the best tool to compare the "new" database schema with the existing
"old" db schema , and save the differences( probably in a script) then be
able to apply those changes at the customer site.  I have about 300
customers databases that will need  to be updated.
OR, are there any 3rd party D7 components that do this?

Thanks for any ideas.  I have looked at Red-Gate which looks ok.

TIA
DAN