[setr]

The part that’s weird with nulls is that it’s a trinary logic stuffed into a boolean algebra. The use of x = NULL instead of x IS NULL is pretty much always a mistake.

More importantly, x = value instead of (x = value and x IS NOT NULL) is almost always a mistake, and a stupidly subtle one at that. And for this curse, we get… nothing particularly useful from these semantics.

Also the x != NULL case is completely cursed

[grahamlee]

> The part that’s weird with nulls is that it’s a trinary logic stuffed into a boolean algebra.

It's a three-valued logic (though not trinary, which would use a base-3 number system) in a three-valued algebra: specifically, the relational algebra. The outcome of a logical test has three values: true, false, or NULL; this is distinct from Boole's algebra where outcomes have a continuous value between 0 and 1 inclusive.