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Order of execution 2+ messages / 2 participants [nested] [flat]
* Order of execution @ 2013-05-06 00:04 JORGE MALDONADO <jorgemal1960@gmail.com> 0 siblings, 1 reply; 2+ messages in thread From: JORGE MALDONADO @ 2013-05-06 00:04 UTC (permalink / raw) To: pgsql-sql I have an UPDATE query which performs several opertions in one table. UPDATE table01 SET field1 = (query1 may contain any field), field2 = (query1 may contain any field), field3 = (query1 may contain any field) WHERE (condition) query1, query2 and query3 perform a logic to determine which records will be updated. Does field1 updates first, then field2 and, lastly, field3? or What is the order in which updates are executed? If I need fields to be updated in a certain order, should I use 3 UPDATE commands instead? Respectfully, Jorge Maldonado ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Order of execution @ 2013-05-06 09:07 Jasen Betts <jasen@xnet.co.nz> parent: JORGE MALDONADO <jorgemal1960@gmail.com> 0 siblings, 0 replies; 2+ messages in thread From: Jasen Betts @ 2013-05-06 09:07 UTC (permalink / raw) To: pgsql-sql On 2013-05-06, JORGE MALDONADO <jorgemal1960@gmail.com> wrote: > --089e013d1eb83325e504dc01710d > Content-Type: text/plain; charset=ISO-8859-1 > > I have an UPDATE query which performs several opertions in one table. > > UPDATE table01 SET > field1 = (query1 may contain any field), > field2 = (query1 may contain any field), > field3 = (query1 may contain any field) > WHERE (condition) > > query1, query2 and query3 perform a logic to determine which records will > be updated. Does field1 updates first, then field2 and, lastly, field3? Updates are one row at a time in an unpredictble order. this will be wrapped in a transaction so either all will updated or none. testing suggests that in simple cases the expressions are evaluated in the order the columns appear in the table definition, but I wouldn't rely on that. > or What is the order in which updates are executed? If I need fields to be > updated in a certain order, should I use 3 UPDATE commands instead? yeah, if "simultaneously" isn't acceptable you'll need to do separate updates. -- ⚂⚃ 100% natural -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2013-05-06 09:07 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2013-05-06 00:04 Order of execution JORGE MALDONADO <jorgemal1960@gmail.com> 2013-05-06 09:07 ` Jasen Betts <jasen@xnet.co.nz>
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