Re: accessing currval(), How? ... Trigger? I think...???

On Tue, 2003-02-11 at 07:38, Ralph Rotondo wrote:

> What I want to do is take the value used for contact_id by the sequence
> contact_id_seq and insert it into a matching field in table contact_lists,
> (In other words I want everybody entered in the db to get a contact_list
> assigned to them linked via their contact_id).
>
> I can do this from the commandline using:
>
> SELECT currval('"contact_id_seq"');
>
> I have had no success accessing the currval() function through PHP trying
> every possible combo of single & double quotes and have reached the
> conclusion that the currval() function is simply unreachable from outside
> postgres. So I tried to create a pl/pgsql function to be called by a
> trigger.

There's nothing special about accessing currval from outside
postgresql. psql uses the libpq interface, just like everything else.

I wonder if your problem is that you are not getting the same database
session each time? currval() only works in the *same* session that
nextval() was called in. Since http is stateless, you would need to
provide a means to connect to the same session; any other would give a
failure, or even the wrong result (if someone else had called nextval
and you had inherited that session). Perhaps you should arrange to
store the nextval result with a key that can be retrieved from any
session.

If it is the session that is the problem, wrapping currval in a function
will make no difference at all.

--
Oliver Elphick Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
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