missive(at)frontiernet(dot)net (Lee Harr) writes:
> The table should look like:
> CREATE TABLE AA (t timestamp default current_timestamp
> CHECK (t = current_timestamp));
I don't think this is possible or sensible. A constraint is an
assertion, it should be valid whenever you check it (with the
single exception that DEFERRED constraints don't have to hold
intra-transaction).
I think what you really want is an ON INSERT OR UPDATE trigger that sets
the value of t to current_timestamp (regardless of what the user tried
to put in the column). You don't need a constraint, and you don't even
need a default --- the default just represents a wasted function call,
if you do it this way.
regards, tom lane