Identifying vs Non-Identifying Relationships (Again!!!)

Question

So, I\'ve read a whole lot of answers here on stackoverflow, but I\'m still confused about the whole concept thereof. Specifically, I\'ve gone over this article (including a

Answer 1

Joel has provided a good answer (+1 to him), let me just offer a small mental shortcut that you can use when thinking about identifying relationships... just ask yourself:

Can I achieve uniqueness only with the attributes of the child entity?

If no, and you need to include the attributes migrated from the parent into the child key to make it unique, then you have an identifying relationship¹. It's about identification-dependence, not existence-dependence²!

You might be interested in this post for some more musings on the topic.

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¹ And the child entity is "weak" or "dependent".

² Although identification-dependence usually implies existence-dependence.