Entity Relationship Diagram - Relationship Strength?

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Published on 2010-04-15T19:19:53Z Indexed on 2010/04/15 19:23 UTC
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Hi,

I am trying to figure out under what circumstances I should use weak (non-identifying) relationships (where the primary key of the related entity does not contain a primary key component of the parent entity), verses when I should use strong (identifying) relationships (primary key of the related entity contains a primary key component of the parent entity).

For example, when designing an Entity Relationship Diagram , if I have two entities, (e.g. book and purchaser), how do I know when to choose the solid Crows Foot or the dashed Crows Foot to connect the two entities?

Any assistance will be appreciated. Thanks in advance.

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