Обсуждение: altering domains, allowing null

How can I alter domain, to allow it to be null ?
I can set it to be NOT NULL, but there's now way to achieve the opposite effect.
At least I can't find a way. Any ideas please ? (8.3+)

--
GJ

nvm. I figured it out seconds after sending that email (despite
spending 10 mins on it prior to).
for the record:
 alter DOMAIN xxx DROP NOT NULL ;