On 2009-06-10, johnf <jfabi...@yolo.com> wrote: > Hi, > I'm am programming in python using the Dabo modules. www.dabodev.com if your > interested. Dabo is a framework that provides an easy way to build desktop > app's. To clear a data entry form. I have been setting the where clause > to "where 1=0". This of course retrieves 0 records and my form will display > nothing. It has been suggested that it might be better to set the where > clause to a primary key value that does not exist in the table "where PK >= -9999999".
"where PK=NULL" is better as anything=NULL is never true. PK=-9999999 may be true sometimes. As Tom says PK=-9999999 causes postgres to look for a record that matches, PK=NULL doesn't cause needless search. that said if -9999999 is outside of the valid range for PK then the search will finish very quickly as at worst only a sigle btree page will need to be loaded. in order of preference. no query at all where FALSE where PK=NULL where PK=-9999999 (note that this one may not work) -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
