I have a dataset that has multiple identifiers, and I want to check for duplicates across each of them. For example, each row has ID1, ID2, and ID3. I want to know if ID1 from one row matches to ID2 or ID3 in another row (not within the same row). I can't think of an easy way to do this without restructuring the dataset. I'd prefer to do this check in SQL but can't figure out how. But I'd be satisfied with being able to do this check without restructuring. All I would want to do is identify the ID1 value that matches to ID2 or ID3 in another row. Suggestions appreciated.
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