Обсуждение: Java and Currval

I'm having trouble getting the currval function to work from a Java
program (or from Postgres at all). I want to get the value of addressid
in the table taddress. The best I seem to be able to come up with is
'SELECT currval(taddress.addressid)'. However this gives me the error
'ERROR:  relation "1" does not exist' or whatever the number should be.
I've tried lots of variations but can't seem to work it out. What am I
doing wrong? Thanks.

-Sam

On Mon, May 02, 2005 at 05:30:12PM +0100, Sam Adams wrote:
>
> I'm having trouble getting the currval function to work from a Java
> program (or from Postgres at all). I want to get the value of addressid
> in the table taddress. The best I seem to be able to come up with is
> 'SELECT currval(taddress.addressid)'.

The argument to currval() is a quoted sequence name, so you probably
need something like this:

SELECT currval('taddress_addressid_seq');

In PostgreSQL 8.0 you can use pg_get_serial_sequence() to get the
sequence name from the table and column names:

SELECT currval(pg_get_serial_sequence('taddress', 'addressid'));

-- 
Michael Fuhr
http://www.fuhr.org/~mfuhr/

Hi,

On 5/2/05, Sam Adams <samadams@myfastmail.com> wrote:
> I'm having trouble getting the currval function to work from a Java
> program (or from Postgres at all). I want to get the value of addressid
> in the table taddress. The best I seem to be able to come up with is
> 'SELECT currval(taddress.addressid)'. However this gives me the error
> 'ERROR:  relation "1" does not exist' or whatever the number should be.
> I've tried lots of variations but can't seem to work it out. What am I
> doing wrong?

You should use the sequence as parameter to currval(), like:

=> \d products
Table "public.products"
-[ RECORD 1 ]----------------------------------------------------------
Column    | proid
Type      | integer
Modifiers | not null default nextval('public.products_proid_seq'::text)
=> SELECT currval(products.proid);
ERROR:  relation "1" does not exist
=> SELECT currval('public.products_proid_seq'::text);
nextval
---------     7
(1 row)

Regards.

On Mon, May 02, 2005 at 17:30:12 +0100, Sam Adams <samadams@myfastmail.com> wrote:
> I'm having trouble getting the currval function to work from a Java
> program (or from Postgres at all). I want to get the value of addressid
> in the table taddress. The best I seem to be able to come up with is
> 'SELECT currval(taddress.addressid)'. However this gives me the error
> 'ERROR:  relation "1" does not exist' or whatever the number should be.
> I've tried lots of variations but can't seem to work it out. What am I
> doing wrong? Thanks.

I don't know what JAVA brings to the mix, but the argument to currval
is a string. Before version 8 you would do something like:
SELECT currval('taddress_addressid_seq')
This string isn't guaranteed to work, but would normally be the correct
one. In 8.0 there is a function that will return the sequence name.
Note that you must have also done a nextval or setval call on that
sequence in the current session or the value is undefined and trying to
access it will result in an error.