Tweak Brian's PR a bit.
Tweak Brian's PR a bit.

I think the safest thing to do is make all nullable columns
`NULL DEFAULT NULL`, since different databases do weird things
with timestamp columns (e.g. adding `DEFAULT CURRENT_TIMESTAMP`
or coercing `null` values `now()`!).

TeamHG-Memex/agnostic,TeamHG-Memex/agnostic