Bob,
There is several ways to tackle this. You are already doing the brute force method. The most elegant is to write some code that would ingest the file and then update the records.
There is a third way with Pipelines. I would create another Quickbase application call it Vendor Data or something like that. You do not even need any relationships. Here is the structure
You need three steps in your Pipeline. It starts when you import records to the Vendor Data Table
The Search Step finds the matching record by Random Number
Then it updates the records in the Existing Table.
Reach out if this does not make sense.
