I am trying to append or update from 1 table to another. They both have the same structure. I cannot make changes to the source table as it beelongs to another company. The source table has no unique field, however, a combination of 3 fields is unique. So I set an index in the target table consisting of these 3 fields. I must evaluate each record in the source table, if it does not exist in the target table I append it. If it does exist, I must see if it has been updated and if so, update the appropriate fields. This is working o.k. but it is very slow as the target table continues to grow and my do while not eof() and seek commands seem to be the only way to make my updates. Any suggestions would be appreciated.

for example the 2 tables have fields A - E.
None are unique but A + B + C is unique

use table 1
do while not eof()
store A + B + C to memvar
use table 2
seek A + B + C
if found()
if fields D + E dont match
update
endif
else
append record from table1
endif
skip
enddo