Update database from imported table

[dmcintyre]

I have a Table A in the main database that I require to be updated with
information that is imported from the web and then placed in Table B in the
same database.
So far so good, I need to update Table A from Table B only when the primary
keys match. In addition I would like to monitor/record the changes.
Table B will be updated daily and may or may not contain the records in
Table A. If in Table B but not in Table A then Table A needs to have an
append action.
The end result would be a Table A that contains the most current and
complete data, Table B is cleared down prior too the next days import.

Any advice or ideas will be very welcome

Don