Why should we use SKU since we have unique IDs

Question

We use a unique id to sync products between our application and retailers.

Most of application are using SKU to identify the product, BUT why should we use a second id (SKu) if we already have one (primary incremental id key) ?

Answer 1

Primary keys are mainly for database use. When a database references an item, it does not care for the structure of the primary key, on that it's unique

Although this could mean we could use many different forms, the reality is you want to keep your architecture as efficient & simple as possible. SKU's and other details (as referenced by sqlvogel) are attributes of particular database objects, and can change with time. Primary keys do not

Answer 2

SKU means a Stock Keeping Unit - a item or product that you stock. The question is what identifier(s) will customers and business users be using to identify SKUs. Often that's called a SKU code or just SKU for short. If you already have such an identifier then maybe you don't need another one, although it's perfectly reasonable and not uncommon to have different identifiers for different purposes (e.g. a bar code and a customer-friendly product code).