Fwd: Getting ID of last-inserted row

From: David <wizzardx(at)gmail(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Fwd: Getting ID of last-inserted row
Date: 2009-05-20 10:35:08
Message-ID: 18c1e6480905200335q9bb1023ube062bfd3018aba8@mail.gmail.com
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>> I never found an adequate (simple and efficient) method for getting
>> the primary key ID of the just-inserted row, and usually used
>> transactions and "select last value, ordered by id"-type queries to
>> get the last id value, or other ugly logic.
>
> use currval() instead, see
> http://www.postgresql.org/docs/current/static/functions-sequence.html
> --

I think I researched that before also, but I wasn't sure at the time
how safe it was against race conditions. Although I see now (reading
the docs again) that it is tracked for different sessions so it should
be safe. There might also be issues (for instance, where you are using
a complex database-handling library), where you can't always guarantee
that your currval() call is made at the right time. But most of the
time it should be fine. Thanks for the reminder.

> Also, you can do insert....returning... (as of version 8.2, I think):
>
> INSERT INTO clients (id, name)
>  VALUES (nextval('clients_id_seq'), 'John Smith')
>  RETURNING id;

Thanks. I think I saw that too, not too long ago, but forgot about it.
Some of the PostgreSQL services I use are on older versions, so I need
to use older syntax. But, this will be useful when the db version is
guaranteed to be recent. Thanks also for your reminder.

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