From: Ries van Twisk <ries@jongert.nl>
To: 'Ajit Aranha' <ajit_aranha@rocketmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: Null not equal to '' (empty)
Date: Fri, 27 Sep 2002 14:40:06 +0200
Message-ID: <000001c26623$02f515a0$f100000a@IT001> (raw)
In-Reply-To: <20020920060916.42881.qmail@web14104.mail.yahoo.com>
This is because '' is not equal to NULL
'' Means a empty string
NULL means a empty set
So this: SELECT * FROM tbl WHERE c1 IS NULL;
is totally different then: SELECT * FROM tbl WHERE c1='';
Ries
-----Oorspronkelijk bericht-----
Van: pgsql-sql-owner@postgresql.org
[mailto:pgsql-sql-owner@postgresql.org]Namens Ajit Aranha
Verzonden: vrijdag 20 september 2002 8:09
Aan: pgsql-sql@postgresql.org
Onderwerp: [SQL] Null not equal to '' (empty)
Why is ''(empty) not equal to null? Its a major headache when porting
from other RDBMS like Oracle. Anyone knows any easy workarounds?
i.e. if you use: create table tbl (
c1 varchar(5));
insert into tbl values ('');
select * from tbl where c1 is null; will return
zero rows.
Also try this: select TO_DATE('','DD-MM-YY'); and
this TO_DATE('','DD-Mon-YY');
;-)
-Ajit (ajit_aranha@rocketmail.com)
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To: pgsql-sql@postgresql.org
Cc: ries@jongert.nl, ajit_aranha@rocketmail.com
Subject: Re: Null not equal to '' (empty)
In-Reply-To: <000001c26623$02f515a0$f100000a@IT001>
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