Re: <> '' in PL/SQL

Yes, you're right.
And <> '' or <> NULL is as useful as 1 <> 1 or 1 = 1. These two codes have the same effect:

if a <> null /* or a <> '' */ then

   null; /* this part never executes */ else

   <something>
end;

if 1 = 1 then

   <something>
end;

Norris a écrit dans le message <7rn3ke$oaq15_at_imsp212.netvigator.com>...
>So, <> '' is same as <> NULL which is useless in PL/SQL, am I right?
>
>Michel Cadot <micadot_at_netcourrier.com> wrote:
>: 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/
>
>
>
>--
>--
>http://www.washington.edu/pine/faq/
Received on Wed Sep 15 1999 - 02:57:23 CDT