see enclosed screenshot..
I thought, the record still locked that's why it returns empty..
On Thu, May 16, 2019 at 9:21 PM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:
> On 5/16/19 7:10 AM, Winanjaya Amijoyo wrote:
> > Hi David,
> >
> > thanks for your advise, as I am new with postgresql..
> > I try to use LOCK as below, but it does not returning pid?
> > what I missed?
>
> I'm not sure which pid you are referring to, the INSERT or UPDATE or both?
>
> Can you show the output of the query?
> >
> > BEGIN TRANSACTION;
> > LOCK TABLE test IN ACCESS EXCLUSIVE MODE;
> > WITH s AS (
> > SELECT pid FROM test WHERE area = 'test4'
> > ), i AS (
> > INSERT INTO test (area)
> > SELECT 'test4'
> > WHERE NOT EXISTS (SELECT 1 FROM s)
> > RETURNING pid
> > )
> > UPDATE area
> > SET last_update = CURRENT_TIMESTAMP
> > WHERE pid = (SELECT pid FROM s UNION SELECT pid FROM i)
> > RETURNING pid;
> > COMMIT TRANSACTION;
> >
> >
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>
