Re: setting the where clause - Mailing list pgsql-sql

From Tom Lane
Subject Re: setting the where clause
Date
Msg-id 347.1244643554@sss.pgh.pa.us
Whole thread Raw
In response to setting the where clause  (johnf <jfabiani@yolo.com>)
Responses Re: setting the where clause  (Rob Sargent <robjsargent@gmail.com>)
List pgsql-sql
johnf <jfabiani@yolo.com> writes:
> 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".   

Whoever said that doesn't know what they're talking about.  It's not
faster (because it forces an actual index probe to happen) and it's not
safer (what if one day that PK value exists?).

I'd personally go with "where false"; why not say what you mean rather
than forcing humans and computers to deduce that the condition is
constant false?
        regards, tom lane


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