Hi all,
That is not correct José, you can have entities without an identifier attribute:

But you cannot have an entity without attributes, so you need to have at least one:

In the end entities (tables) have attributes (columns).
Edit 1 - fix the mix of use between entities/tables nomenclature.
Edit 2- just for the record and some context, José Gonçalves deleted its post where he was stating an identifier attribute was required.
Regards,
Rúben