-----Original Message----- From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx] On Behalf Of David Salisbury Sent: Monday, October 17, 2011 3:41 PM To: John R Pierce Cc: pgsql-general@xxxxxxxxxxxxxx Subject: Re: exclusive OR possible within a where clause? Perhaps what I'm hoping to do got munged. In essence it's equivalent of.. create table test ( something numeric ); insert into test values ( 1 ); insert into test values ( 2 ); select * from test where ( something = 1.5 + .5 ) or ( something = 1.5 - .5 ); something ----------- 1 2 (2 rows) select * from test where ( something = 1.5 + .5 ) <> ( something = 1.5 - .5 ); something ----------- 1 2 (2 rows) ( which is of course equivalent of where something = 1 or something = 2 ) In my fabled XOR, I'd get the first one it matched, say something = 1, and the something = 2 would then be ignored/dropped. ---------------------------------------------------------------------------- ------------- 1) There is no concept of "FIRST" since you failed to include an ORDER BY clause 2) Given that "something" can only take on a single value comparing it against two separate (and different) values renders the difference between OR and XOR meaningless. If you want good help you need to give good examples - preferably real ones. What you are trying to do has NOTHING to do with XOR. Provide a more informative description of WHAT you are trying to do and additional REAL sample data. From what you've described here, though, you probably want to use WINDOW functions (RANK/ROW_NUMBER) in a sub-query and then look for only those rows with RANK/ROW_NUMBER equal to 1. David J. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
