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Re: <> '' in PL/SQL

From: Michel Cadot <micadot_at_netcourrier.com>
Date: Tue, 14 Sep 1999 16:13:25 +0200
Message-ID: <7rll7h$brp$1@oceanite.cybercable.fr>


No, you can't use that because " is not '' " is not part of the SQL syntax, you have to use " is not null ".

When i say '' is the same as null, i just mean that '' indicates a null string as the keyword null does. See:

v734>l
  1 declare
  2 begin
  3 if '' is not null then
  4 dbms_output.put_line(''''' is not null');   5 else
  6 dbms_output.put_line(''''' is null');   7 end if;
  8* end;
v734>/
'' is null

PL/SQL procedure successfully completed.

Norris a écrit dans le message <7rlhi1$77u2_at_imsp212.netvigator.com>...
>If '' is the same as NULL then can I use:
>" is not '' " instead of " is not null " ?
>
>Michel Cadot <micadot_at_netcourrier.com> wrote:
>: You have to change <> '' to is not null.
>: As a matter of fact, '' is the same as NULL in PL/SQL
>: so <> '' cannot be true and else part is execute.
>
>: v734>l
>: 1 declare
>: 2 abc varchar2(1);
>: 3 begin
>: 4 abc := 'a';
>: 5 if abc is not null then
>: 6 dbms_output.put_line(abc||' <> empty');
>: 7 else
>: 8 dbms_output.put_line(abc||' = empty');
>: 9 end if;
>: 10* end;
>: v734>/
>: a <> empty
>
>: PL/SQL procedure successfully completed.
>
>
>: Norris a écrit dans le message <7rl8s6$4qs$1_at_adenine.netfront.net>...
>:>I am writing some simple PL/SQL , but I cannot intepret the result:
>:>
>:>set serveroutput on
>:>declare
>:>abc varchar2(1);
>:>begin
>:>abc := 'a';
>:>if abc <> '' then
>:> dbms_output.put_line(abc||' <> empty');
>:>else
>:> dbms_output.put_line(abc||' = empty');
>:>end if;
>:>end;
>:>
>:>
>:>The Result
>:>----------
>:>ServerOutput ON
>:>Statement processed.
>:>a = empty
>:>
>:>
>:>
>:>
>:>
>:>
>:>--
>:>- Have several nice days...
>:>- Opinions are mine and do not necessarily reflect those of the Corp.
>:>http://www.ntfaq.com
>:>http://www.cyberport.com/~tangent/programming/winsock/
>
>
>
>--
>--
>http://www.washington.edu/pine/faq/
Received on Tue Sep 14 1999 - 09:13:25 CDT

Original text of this message

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