Strategy for storing supplemental data alongside imported data

Question

I have ran into this problem a few times and I am wondering what other people are doing.

When I am creating a database, sometimes I have to import data into a table

Answer 1

Well, when you do the import, import into a temp table, and then update the records in the production table (update in the generic sense of the word: delete what's deleted, add what's new, modify what's changed).

You might also want to check out the new MERGE SQL command in 2008, it just might turn out to be very helpful for this case.