Yes! NULL is relational for “don’t know”, and SQL is (mostly, with varying degrees of success) designed to treat is as such. That’s why NULL=anything is NULL and not e.g. false (and IMO it’s a bit of a misfeature that queries that branch on a NULL don’t crash, although it’s still better than the IEEE 754 NaN=anything outright evaluating to false). If the value is funky but you do know it, then store a funky value, not NULL.
