From: | Bruno Wolff III <bruno(at)wolff(dot)to> |
---|---|
To: | Gene Vital <genevital(at)karibe(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Parent Id |
Date: | 2003-10-09 20:20:16 |
Message-ID: | 20031009202016.GB15173@wolff.to |
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Thread: | |
Lists: | pgsql-general |
On Thu, Oct 09, 2003 at 15:55:27 -0400,
Gene Vital <genevital(at)karibe(dot)com> wrote:
> have an example :)
>
> Bruno Wolff III wrote:
>
> >On Thu, Oct 09, 2003 at 14:26:21 -0400,
> > Gene Vital <genevital(at)karibe(dot)com> wrote:
> >
> >>when inserting new records into parent / child tables, what is the best
> >>recommended way of retrieving the pkey value from the parent table when
> >>using auto incrementing fields ?
> >
> >
> >You want to use currval. currval will return the last value obtained
> >by nextval in the same session, so it is safe to use without any additional
> >locking.
> >
You would do something like:
insert into parent_table (pk, col1, col2) values (default, 'val1', 'val2');
insert into child_table (pk, parent, col1, col2)
values (default, currval('parent_table_pk_seq'), 'val3', 'val4');
I don't remember when being able to use default in insert statements was
added. You may need to just leave the pk columns off the list. I added them
so that you could see what the normal sequence name looks like. I also
assume that the two pk columns are declared to be of type serial. If not,
then you have to do the sequence and default creation yourself.
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