database table merging tips with R

Actually, based on my reading of the DBI reference, you should be able
to do the following to create a table (although possibly not temporary):

 dbWriteTable(connection, "r_user_ids", r)

Then you can use the following to drop the table:

 dbRemoveTable(connection, "r_user_ids")

Of course, I don't know whether the ODBC driver implements these
functions or not.  (Is 'RODBC' built on DBI?  Looks like Aaron and I
have been assuming that.)