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.kla...@aklaver.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.kla...@aklaver.com >
