Message-Id: <10645.118868@fatcity.com> From: Alex Hillman Date: Tue, 10 Oct 2000 10:30:59 -0400 Subject: RE: NULL value 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@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@paktel.com [SMTP:awaisb@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@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@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@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@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 RE: NULL value

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@Ora= njewoud.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@paktel.com = [SMTP:awaisb@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@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@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@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@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 =