RE: comparing null values

From: Mercadante, Thomas F <NDATFM_at_labor.state.ny.us>
Date: Thu, 30 Jan 2003 12:55:40 -0800
Message-ID: <F001.0053F904.20030130125540@fatcity.com>

Gary,

it's a definition thing. a null value belongs to the null set. relational theory says that the null set may not be compared to anything else. it is simply not there.

this is different from "1 is not equal to 2".

Tom Mercadante
Oracle Certified Professional

-----Original Message-----
Sent: Thursday, January 30, 2003 2:27 PM To: Multiple recipients of list ORACLE-L

Why is this?? If I know that value X has no value, I certainly know that value X is not like '%STU%' ?????

>From: "Whittle Jerome Contr NCI" <Jerome.Whittle_at_scott.af.mil>
>To: <ORACLE-L_at_fatcity.com>
>CC: <fred_fred_1_at_hotmail.com>
>Subject: RE: comparing null values
>Date: Thu, 30 Jan 2003 13:15:33 -0600
>
>Gary,
>
>Null has no value. It can't be like or not like anything. If you want to
>see the null you'll need to add OR IS NULL to your Where clause.
>
>Jerry Whittle
>ASIFICS DBA
>NCI Information Systems Inc.
>jerome.whittle_at_scott.af.mil
>618-622-4145
>
> > -----Original Message-----
> > From: Gary Jackson [SMTP:fred_fred_1_at_hotmail.com]
> >
> > Can anyone explain why it is that I seem unable to use 'like' and 'not
>like'
> > on columns containing null values. (I am unable to find information
> > regarding this on MetaLink.)
> >
> > For example:
> >
> > SQL> select * from tester2;
> >
> > COL1 COL2 WHATEVER
> > ---- ---- --------
> > 1 1 STUFF
> > 2 2 STUFF
> > 3 3
> > 4 4
> >
> > SQL> select * from tester2 where whatever not like '%STU%';
> > no rows selected
> >
> >
> > My question is why does this not return the 3 & 4 columns?
> >

---

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Author: Gary Jackson
  INET: fred_fred_1_at_hotmail.com

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Author: Mercadante, Thomas F
  INET: NDATFM_at_labor.state.ny.us

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Received on Thu Jan 30 2003 - 14:55:40 CST