[wongarsu]

Yeah, in hindsight the world would be a slightly better place if SQL didn't include NULL, but instead "UNKNOWN" and "NONE", with "NONE = NONE" being true, and "UNKNOWN = UNKNOWN" being unknown.

[stouset]

Or have an Option (or Maybe) type. This is how modern programming languages solve the nil issue, I don't see a reason why a database couldn't take the same approach.

[kzrdude]

When would NONE show up and when would UNKNOWN show up?

[wtetzner]

NONE would mean “there is no value”, and UNKNOWN “there might be a value, but I don’t know what it is”.