In the Leads and Contacts module, Email by default is marked as “Unique” and you can use that field to identify which records are updated in the import.
Perhaps you have a bunch of form or survey responses in a spreadsheet, or a list of attendants at a conference or event, and you want to use that list to update Contact records to show they attended or responded. If you have their emails, you can update your spreadsheet as it is and match based on that field—CRM will correctly find the record to update.
IDs are ALWAYS unique in Zoho and there is never a chance of updating the wrong record. Every record in any module anywhere in Zoho has a unique record ID (Leads, Deals, Tasks, Invoice, Sales Orders, Bill Items, Desk Tickets, etc.)
You can find the record ID in a few places:
If you have that ID readily available in your Excel/CSV, you can choose to update records and match based off of that column.
If another field in your module is marked as “Unique”, like the Account Name in the accounts module, then you can match records based on that. However, make sure spelling and capitalization exactly matches!
You can check to see if a field is marked as “Unique” in the module builder and the specific field settings.