Postgresql update each row with a random value

Question

This is similar to other questions but it appears to vary on a database-by-database implementation. I am using postgres and things like NEWID do not appear to exist.

This is what I want to work:

update foo set bar = (select floor(random() * 10) + 1);

I understand why it doesn't but I can't seem to find a suitable solution that works for Postgres. I want the value of bar to be a random number between 1 and 10 that differs per row.

Answer 1

I think that Postgres might optimize the subquery. Doesn't this work?

update foo
   set bar = floor(random() * 9 + 1);  -- from 1 to 10, inclusive

Answer 2

update foo set bar = floor(random() * 10) + 1;