Select "primary Key or Column" to import/Update product list

Hello,

I am trying to import vendor price list to update current products, I would like to select different primary key/column than Ref or Barcode to avoid duplications and errors.

Simply because i have no barcode data and also no match between the imported list and current ref code of products.

However both my data base and imported list are matched in a different key/column. For example Local Authority Registration Code= DDC CODE which already added as parameter (Unique number like barcode)

I need to select the DDC CODE as primary key/column for updating to avoid errors and duplications.

Appreciating your reply with easy solution

Regards