Thom Brown, 28.10.2011 10:10:
On 28 October 2011 08:29, Thomas Kellerer<spam_ea...@gmx.net> wrote:
Hello,
I just noticed that Postgres allows the following syntax:
create table foo
(
id integer constraint id_default_value default 42
);
But as far as I can tell the "constraint id_default_value" part seems to be
only syntactical sugar as this is stored nowhere. At least I couldn't find
it going through the catalog tables and neither pg_dump -s or pgAdmin are
showing that name in the generated SQL source for the table.
It's not important, I'm just curious why the syntax is accepted (I never saw
a default value as a constraint) and if there is a way to retrieve that
information once the table is created.
It would do something with it if you actually defined a constraint
after it, but since you didn't, it throws it away since there's
nothing to enforce. So if you adjust it to:
create table foo
(
id integer constraint id_default_value check (id> 4) default 42
);
a constraint for that column will be created with the specified name.
Thanks, makes somewhat sense.
I'm wondering why this doesn't throw an error then.
Regards
Thomas
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