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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
>
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-- 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>> -----Original Message-----</FONT> <BR><FONT SIZE=3D2>> From: awaisb_at_paktel.com = [SMTP:awaisb_at_paktel.com]</FONT> <BR><FONT SIZE=3D2>> Sent: Tuesday, October 10, 2000 12:26 PM</FONT> <BR><FONT SIZE=3D2>> To: Multiple recipients of list = ORACLE-L</FONT> <BR><FONT SIZE=3D2>> Subject: NULL = value</FONT> <BR><FONT SIZE=3D2>> </FONT> <BR><FONT SIZE=3D2>> Hi,</FONT> <BR><FONT SIZE=3D2>> I have a logical question, any one who can make = it clear.</FONT> <BR><FONT SIZE=3D2>> create table a = (x number(2) unique);</FONT> <BR><FONT SIZE=3D2>> insert into a = values (null);</FONT> <BR><FONT SIZE=3D2>> 1 row = created.</FONT> <BR><FONT SIZE=3D2>> insert into a = values (null);</FONT> <BR><FONT SIZE=3D2>> 1 row = created.</FONT> <BR><FONT SIZE=3D2>> Q:- I have a table 'A' have one field 'X' with = unique constraint, so a</FONT> <BR><FONT SIZE=3D2>> unique index will be created for it. I inserted = null into this field two</FONT> <BR><FONT SIZE=3D2>> times (or more then it). </FONT> <BR><FONT SIZE=3D2>> </FONT> <BR><FONT SIZE=3D2>> If null is a value, Why these null stored into = table which have unique</FONT> <BR><FONT SIZE=3D2>> constraint?</FONT> <BR><FONT SIZE=3D2>> If null is not a VALUE then what it is?</FONT> <BR><FONT SIZE=3D2>> Is there some special character for = NULL?</FONT> <BR><FONT SIZE=3D2>> If null is not a value why we have operators = for null?</FONT> <BR><FONT SIZE=3D2>> </FONT> <BR><FONT SIZE=3D2>> Regards</FONT> <BR><FONT SIZE=3D2>> </FONT> <BR><FONT SIZE=3D2>> Muhammad Awais</FONT> <BR><FONT SIZE=3D2>> System Developer</FONT> <BR><FONT SIZE=3D2>> Paktel Ltd. Pakistan</FONT> <BR><FONT SIZE=3D2>> Mob. 0303 7757077</FONT> <BR><FONT SIZE=3D2>> (92-51) 111-222-111-282</FONT> <BR><FONT SIZE=3D2>> </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: </FONT> <BR><FONT SIZE=3D2>> INET: awaisb_at_paktel.com</FONT> <BR><FONT SIZE=3D2>> </FONT> <BR><FONT SIZE=3D2>> Fat City Network Services -- = (858) 538-5051 FAX: (858) 538-5051</FONT> <BR><FONT SIZE=3D2>> San Diego, = California -- Public Internet = access / Mailing Lists</FONT> <BR><FONT SIZE=3D2>> = --------------------------------------------------------------------</FO= NT> <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 from). You may</FONT> <BR><FONT SIZE=3D2>> 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> INET: Kirsten.deWeerd_at_Oranjewoud.nl</FONT> </P> <P><FONT SIZE=3D2>Fat City Network Services -- (858) = 538-5051 FAX: (858) 538-5051</FONT> <BR><FONT SIZE=3D2>San Diego, = California -- 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