I have maybe 6000 contacts in Zoho CRM with some user defined fields
including one called Serial which essentially is a unique numeric
identifier for each contact that makes sense to us.
I also have some financial data from another system that also uses
the same serial and which as other useful fields like total sales.
My goal is to update Zoho with the financial fields monthly based
on a look up (to use excel terminology) of the same Serial number.
How do I most easily do this do this ?