Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> RE: NULL value

RE: NULL value

From: Alex Hillman <alex_hillman_at_physia.com>
Date: Tue, 10 Oct 2000 10:30:59 -0400
Message-Id: <10645.118868@fatcity.com>


This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible.

------_=_NextPart_001_01C032C6.B5C108E0
Content-Type: text/plain;

        charset="iso-8859-1"

NULL value can be stored in indexes if it is a value of one of columns of a compaund key and there is at least one column in the key with not NULL value. For indexes with a key consisting of one column NULL values are not stored.

Alex Hillman

-----Original Message-----
From: Weerd Kirsten, E.C. de [mailto:Kirsten.deWeerd_at_Oranjewoud.nl] Sent: Tuesday, October 10, 2000 7:50 AM
To: Multiple recipients of list ORACLE-L Subject: RE: NULL value

Hey, I just learned this yesterday :-)

Null-values are neverd stored in indexes, and will not trigger a constraint like UNIQUE ...
So, I suppose NULL is not a value, so what is it. It's like asking : what is nothing ... :-)

> -----Original Message-----
> From: awaisb_at_paktel.com [SMTP:awaisb_at_paktel.com]
> Sent: Tuesday, October 10, 2000 12:26 PM
> To: Multiple recipients of list ORACLE-L
> Subject: NULL value
>
> Hi,
> I have a logical question, any one who can make it clear.
> create table a (x number(2) unique);
> insert into a values (null);
> 1 row created.
> insert into a values (null);
> 1 row created.
> Q:- I have a table 'A' have one field 'X' with unique constraint, so a
> unique index will be created for it. I inserted null into this field two
> times (or more then it).
>
> If null is a value, Why these null stored into table which have unique
> constraint?
> If null is not a VALUE then what it is?
> Is there some special character for NULL?
> If null is not a value why we have operators for null?
>
> Regards
>
> Muhammad Awais
> System Developer
> Paktel Ltd. Pakistan
> Mob. 0303 7757077
> (92-51) 111-222-111-282
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author:
> INET: awaisb_at_paktel.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB ORACLE-L
> (or the name of mailing list you want to be removed from). You may
> also send the HELP command for other information (like subscribing).

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Weerd Kirsten, E.C. de
  INET: Kirsten.deWeerd_at_Oranjewoud.nl

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).

------_=_NextPart_001_01C032C6.B5C108E0
Content-Type: text/html;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Diso-8859-1">
<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
5.5.2448.0">
<TITLE>RE: NULL value</TITLE>
</HEAD>
<BODY>

<P><FONT SIZE=3D2>NULL value can be stored in indexes if it is a value =
of one of columns of a compaund key and there is at least one column in =
the key with not NULL value. For indexes with a key consisting of one =
column NULL values are not stored.</FONT></P>

<P><FONT SIZE=3D2>Alex Hillman</FONT>
</P>

<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2>From: Weerd Kirsten, E.C. de [<A =
HREF=3D"mailto:Kirsten.deWeerd_at_Oranjewoud.nl">mailto:Kirsten.deWeerd_at_Ora=
njewoud.nl</A>]</FONT>
<BR><FONT SIZE=3D2>Sent: Tuesday, October 10, 2000 7:50 AM</FONT>
<BR><FONT SIZE=3D2>To: Multiple recipients of list ORACLE-L</FONT>
<BR><FONT SIZE=3D2>Subject: RE: NULL value</FONT>
</P>
<BR>

<P><FONT SIZE=3D2>Hey, I just learned this yesterday :-)</FONT>
</P>

<P><FONT SIZE=3D2>Null-values are neverd stored in indexes, and will =
not trigger a constraint</FONT>
<BR><FONT SIZE=3D2>like UNIQUE ...</FONT>
<BR><FONT SIZE=3D2>So, I suppose NULL is not a value, so what is it. =
It's like asking : what is</FONT>
<BR><FONT SIZE=3D2>nothing ... :-)</FONT>
</P>

<P><FONT SIZE=3D2>&gt; -----Original Message-----</FONT>
<BR><FONT SIZE=3D2>&gt; From: awaisb_at_paktel.com =
[SMTP:awaisb_at_paktel.com]</FONT>
<BR><FONT SIZE=3D2>&gt; Sent: Tuesday, October 10, 2000 12:26 PM</FONT>
<BR><FONT SIZE=3D2>&gt; To:&nbsp;&nbsp; Multiple recipients of list =
ORACLE-L</FONT>
<BR><FONT SIZE=3D2>&gt; Subject:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; NULL =
value</FONT>
<BR><FONT SIZE=3D2>&gt; </FONT>
<BR><FONT SIZE=3D2>&gt; Hi,</FONT>
<BR><FONT SIZE=3D2>&gt; I have a logical question, any one who can make =
it clear.</FONT>
<BR><FONT SIZE=3D2>&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; create table a =
(x number(2) unique);</FONT>
<BR><FONT SIZE=3D2>&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; insert into a =
values (null);</FONT>
<BR><FONT SIZE=3D2>&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1 row =
created.</FONT>
<BR><FONT SIZE=3D2>&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; insert into a =
values (null);</FONT>
<BR><FONT SIZE=3D2>&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1 row =
created.</FONT>
<BR><FONT SIZE=3D2>&gt; Q:- I have a table 'A' have one field 'X' with =
unique constraint, so a</FONT>
<BR><FONT SIZE=3D2>&gt; unique index will be created for it. I inserted =
null into this field two</FONT>
<BR><FONT SIZE=3D2>&gt; times (or more then it). </FONT>
<BR><FONT SIZE=3D2>&gt; </FONT>
<BR><FONT SIZE=3D2>&gt; If null is a value, Why these null stored into =
table which have unique</FONT>
<BR><FONT SIZE=3D2>&gt; constraint?</FONT>
<BR><FONT SIZE=3D2>&gt; If null is not a VALUE then what it is?</FONT>
<BR><FONT SIZE=3D2>&gt; Is there some special character for =
NULL?</FONT>
<BR><FONT SIZE=3D2>&gt; If null is not a value why we have operators =
for null?</FONT>
<BR><FONT SIZE=3D2>&gt; </FONT>
<BR><FONT SIZE=3D2>&gt; Regards</FONT>
<BR><FONT SIZE=3D2>&gt; </FONT>
<BR><FONT SIZE=3D2>&gt; Muhammad Awais</FONT>
<BR><FONT SIZE=3D2>&gt; System Developer</FONT>
<BR><FONT SIZE=3D2>&gt; Paktel Ltd. Pakistan</FONT>
<BR><FONT SIZE=3D2>&gt; Mob. 0303 7757077</FONT>
<BR><FONT SIZE=3D2>&gt; (92-51) 111-222-111-282</FONT>
<BR><FONT SIZE=3D2>&gt; </FONT>
<BR><FONT SIZE=3D2>&gt; -- </FONT>
<BR><FONT SIZE=3D2>&gt; Please see the official ORACLE-L FAQ: <A =
HREF=3D"http://www.orafaq.com" =
TARGET=3D"_blank">http://www.orafaq.com</A></FONT>
<BR><FONT SIZE=3D2>&gt; -- </FONT>
<BR><FONT SIZE=3D2>&gt; Author: </FONT>
<BR><FONT SIZE=3D2>&gt;&nbsp;&nbsp; INET: awaisb_at_paktel.com</FONT>
<BR><FONT SIZE=3D2>&gt; </FONT>
<BR><FONT SIZE=3D2>&gt; Fat City Network Services&nbsp;&nbsp;&nbsp; -- =
(858) 538-5051&nbsp; FAX: (858) 538-5051</FONT>
<BR><FONT SIZE=3D2>&gt; San Diego, =
California&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -- Public Internet =
access / Mailing Lists</FONT>
<BR><FONT SIZE=3D2>&gt; =
--------------------------------------------------------------------</FO=
NT>
<BR><FONT SIZE=3D2>&gt; To REMOVE yourself from this mailing list, send =
an E-Mail message</FONT>
<BR><FONT SIZE=3D2>&gt; to: ListGuru_at_fatcity.com (note EXACT spelling =
of 'ListGuru') and in</FONT>
<BR><FONT SIZE=3D2>&gt; the message BODY, include a line containing: =
UNSUB ORACLE-L</FONT>
<BR><FONT SIZE=3D2>&gt; (or the name of mailing list you want to be =
removed from).&nbsp; You may</FONT>
<BR><FONT SIZE=3D2>&gt; also send the HELP command for other =
information (like subscribing).</FONT>
<BR><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Please see the official ORACLE-L FAQ: <A =
HREF=3D"http://www.orafaq.com" =
TARGET=3D"_blank">http://www.orafaq.com</A></FONT>
<BR><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Author: Weerd Kirsten, E.C. de</FONT>
<BR><FONT SIZE=3D2>&nbsp; INET: Kirsten.deWeerd_at_Oranjewoud.nl</FONT>
</P>

<P><FONT SIZE=3D2>Fat City Network Services&nbsp;&nbsp;&nbsp; -- (858) =
538-5051&nbsp; FAX: (858) 538-5051</FONT>
<BR><FONT SIZE=3D2>San Diego, =
California&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -- Public Internet =
access / Mailing Lists</FONT>
<BR><FONT =
SIZE=3D2>---------------------------------------------------------------=
-----</FONT>
<BR><FONT SIZE=3D2>To REMOVE yourself from this mailing list, send an =
E-Mail message</FONT>
<BR><FONT SIZE=3D2>to: ListGuru_at_fatcity.com (note EXACT spelling of =
'ListGuru') and in</FONT>
<BR><FONT SIZE=3D2>the message BODY, include a line containing: UNSUB =
ORACLE-L</FONT>
<BR><FONT SIZE=3D2>(or the name of mailing list you want to be removed =
Received on Tue Oct 10 2000 - 09:30:59 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US