How do I implement this multi-table database design/constraint, normalized?

What you'd like to be able to do is express that the join of Elements and Elements_Xref has a unique constraint on Class and Real ID. If you had a DBMS that supported SQL-92 ASSERTION constraints, you could do it.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.

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