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by masklinn
1441 days ago
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> It allows specifying a constraint - that you can't have two rows with the same values even if one of the values is a NULL. That's prohibiting duplicate NULLs. The change allows you to prohibit duplicate NULLs. Sure. > Here, "Kim" is car-less (NULL in the CarID field) twice, which makes no sense. The relation makes no sense to start with, it didn’t need duplicate nulls for that. |
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