Re: Retrieving the new nextval...

On Wed, 28 Aug 2002 18:32:45 +0200 (CEST)
friedrich nietzsche <nietzsche_psql(at)yahoo(dot)it> wrote:

> Hi all,
> I'm in trouble with the same problem, but in PHP..
> With your solution, I cannot be totally sure that last
> inserted raw was mine...
> Because I'm on a web page, it could be that, as soon
> as I've inserted my record, another one do an
> insertion, so I would get the wrong ID...
> does transactions resolve this, in Psql???
> I thought to solve it with a similiar solution,
> working in transactions inserting a raw and
> immedialtly after read from DB last raw, but who
> assure me that all will go right??
> If I was on a server app., I (and you, if it is your
> case) would insert a timestamp, and then I'd select
> from table where timestamp = mysavedtime;
> But in my case there could be two or more equals
> timestamp, cause there's not only one application
> working with DB...
> I'm still reading, searching, trying...
> ciao
> danilo

If your on the same connection, then currval()/nextval() will do the
correct thing. i.e. if this is the same php page, then it should be the same
connection. If not, I would use php's session support to pass the sequence number
onto the next page.

currval()/nextval() are connection safe. As far as I know the php connection system works correctly
(just don't try to use a DBM file at the same time as a pgsql connection... PHP does NOT like that!)

GB

>
>
> --- Kevin Brannen <kevinb(at)nurseamerica(dot)net> ha
> scritto: > 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
> R
>
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--
GB Clark II | Roaming FreeBSD Admin
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