Thread: Re: [SQL] Retrieving the new "nextval" for primary keys....

Greg Patnude wrote:
> I am using postgreSQL with Perl::CGI and Perl::DBI::Pg... I would like to be
> able to insert a row from my Perl script [$SQL->exec();] and have postgreSQL
> return the id of the newly inserted record (new.id) directly to the Perl
> script for further processing... Anyone with a solution / idea ???
>
> Nearly EVERY table I create in postgreSQL (7.2) has the following minimum
> structure:
>
> create table "tblName" (
>
>     id int4 primary key nextval ("tblName_id_seq"),
>
>     ..field...
> )

You can either do it in 2 statements, something like:

$dbh->do("insert into tblName ...");
my ($id) = $dbh->selectrow_array("select currval('tblName_id_seq')");

Or you could create a function which takes the insert statement, and
ends with doing a select on the currval (as above) and returning that.
As I do the 2 statement approach above, I haven't done a function, but
it doesn't look like it would be that hard to do.

HTH,
Kevin

On Wed, 28 Aug 2002 18:36:10 +0200 (CEST)
friedrich nietzsche <nietzsche_psql@yahoo.it> wrote:

>  One solution seems to locking table(s),
> but I prefer to leave it as last chance...
> using table locks, and the trick of writing and
> suddenly reading back from DB it probably works,
> but it doesn't seems so sexy... :)
> ciao
> danilo
>

Why would you have to lock the table?  currval() is connection safe.

I would either do the insert and then do a currval() OR do a nextval()
and do the insert.  Either one would work. I always just do the insert
and then call currval() to get the current serial number for the connection.

GB

--
GB Clark II             | Roaming FreeBSD Admin
gclarkii@VSServices.COM | General Geek
           CTHULU for President - Why choose the lesser of two evils?

 One solution seems to locking table(s),
but I prefer to leave it as last chance...
using table locks, and the trick of writing and
suddenly reading back from DB it probably works,
but it doesn't seems so sexy... :)
ciao
danilo

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