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POIdentifying vs Non-Identifying Relationships (Again!!!)
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copied!<p>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 all the ones it references), but can't seem to find a solid grasp on the concept (or perhaps it is my confusion between cardinality (n:m, etc.) and identities): </p> <p><a href="https://stackoverflow.com/questions/2814469/still-confused-about-identifying-vs-non-identifying-relationships">Still Confused About Identifying vs. Non-Identifying Relationships</a></p> <p>My issue is this: I know that identifying relationships imply that the primary key of a child entity must include its foreign key, and that the opposite is true for non-identifying relationships (Is this correct?). Now, this seems a bit too "forward thinking" to me? The same was also said in one of the comments in one of the links. How can I "take a step back" and actually see <b>which</b> relations are of which identity? </p> <p>For example, I have two dilemmas: </p> <ol> <li><code>job_title</code> (parent, 1) to <code>employee</code> (child, 1..*). Am I right in thinking that, because job_title is a lookup table, it must be a non-identifying relation? Or would it be more accurate in saying that "an employee can't exist without a job_title, thus it must be identifying"? Or would it be the relationship defining that scenario?</li> <li><code>employee</code> to <code>employee_equipment</code> (bridging entity between the m:n cardinality) to <code>equipment</code>. Now, I read that this has to be an identifying relationship on both sides of employee_equipment. But, what if an employee doesn't NEED equipment? Can one have an optional identifying relationship? </li> </ol> <p>I guess that I'm really looking for a way to identify which identity tables should belong to, without thinking of primary/foreign keys, or anything really <i>technical</i> for that matter. </p> <p>Any help would be much appreciated!</p>

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