On Sun, Sep 18, 2005 at 07:40:26PM +0100, ShepherdHill DB Subscriptions wrote: > Hi, > > I have a table with this schema: > > CREATE TABLE billing.bill > ( > sno serial NOT NULL, > billno int4, > det date NOT NULL, > . > . > . > CONSTRAINT bill_pkey PRIMARY KEY (sno) > ) > > I want to execute a query that will not return any record. Which of > these queries is cheaper please? > > 1. Select * from billing.bill where 1=0 > 2. Select * from billing.bill where sno=0 Do an explain analyze and see. :) 1 will be faster because the optimizer can discard it right off the bat. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
