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.klaver@xxxxxxxxxxx> 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.klaver@xxxxxxxxxxx
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