The way I think of it is a key, in a database, is a record key. It is intended to identify a particular logical record, not the logical thing which is referred to by the record.
An an footnote, I'll add this doesn't mean that you need to have complexities like record versioning, record history, or anything. But couched in those conceptual terms where those things are possible, is a happy and safe space to be. In this space, a database records entries, as if they were each a single paper form with boxes where you fill out, in pencil, to erase if you like or not, the particulars of the thing you're recording. This form comes pre-stamped with a number: the record key.
In this cozy little world, you can be imperfect, and mistakenly (or deliberately, as your use case requires), file multiple slips that refer to the same logical thing, and yet all have different file ("record") numbers - or keys.
An an footnote, I'll add this doesn't mean that you need to have complexities like record versioning, record history, or anything. But couched in those conceptual terms where those things are possible, is a happy and safe space to be. In this space, a database records entries, as if they were each a single paper form with boxes where you fill out, in pencil, to erase if you like or not, the particulars of the thing you're recording. This form comes pre-stamped with a number: the record key.
In this cozy little world, you can be imperfect, and mistakenly (or deliberately, as your use case requires), file multiple slips that refer to the same logical thing, and yet all have different file ("record") numbers - or keys.