I have a bunch of data from multiple retailers. Each product that each retailer sells may or may not be sold by another retailer in the database. If multiple retailers sell the same product, then the product can be identified by a SKU. I currently have 1 database for each retailer. I'm having a problem trying to conceptualize an appropriate database schema to identify how many retailers are selling the same product.
Should I have 1 table with all retailers?