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RE: IN() question

From: Pardee, Roy E <roy.e.pardee_at_lmco.com>
Date: Mon, 06 May 2002 08:53:30 -0800
Message-ID: <F001.00458ED6.20020506085330@fatcity.com>


Does this mean that you can't include Null as a value in an IN() clause? That is, would something like:

> SQL> SELECT COUNT(*)
> 2 from leisure_plan_master_temp
> 3 where membership_class = 'D'
> 4 AND pay_METHOD IN (Null, 'C','P');

count rows where pay_METHOD is Null? (Disregarding for the moment the problem Lisa was actually trying to solve.)

Thanks!

-Roy

Roy Pardee
Programmer/Analyst
SWFPAC Lockheed Martin IT
Extension 8487

-----Original Message-----
Sent: Friday, May 03, 2002 5:33 PM
To: Multiple recipients of list ORACLE-L

In any equivalence operation (which includes non-equivalence, too), NULL never returns TRUE -- it just returns NULL which non-TRUE has the same result as FALSE. Only IS and IS NOT operators can be used to evaluate NULLs...

> Slap me if this is a dumb question.
>
> Here's my pay methods
>
> SQL> SELECT ASCII(PAY_METHOD), PAY_METHOD, COUNT(*)
> 2 FROM LEISURE_PLAN_MASTER_TEMP
> 3 WHERE MEMBERSHIP_CLASS = 'D'
> 4 GROUP BY PAY_METHOD;
>
> ASCII(PAY_METHOD) P COUNT(*)
> ----------------- - ----------
> 67 C 42955
> 80 P 34373
> 11786
>
> I expected this statement to return the 11,786 records that have null
> values. However, it doesn't:
>
> SQL> SELECT COUNT(*)
> 2 from leisure_plan_master_temp
> 3 where membership_class = 'D'
> 4 AND pay_METHOD NOT IN ('C','P');
>
> COUNT(*)
> ----------
> 0
>
> But when I do this, I get the answer I expect.
>
> SQL> SELECT COUNT(*)
> 2 from leisure_plan_master_temp
> 3 where membership_class = 'D'
> 4 AND PAY_METHOD IS NULL;
>
> COUNT(*)
> ----------
> 11786
>
> This isn't exactly correct. There may be other values in this field, and
if
> they show up I need to include them, not just records where this field is
> null. What am I missing? Is it because the value is NULL that Oracle
> excludes it from the IN() statement, because of the classic definition of
> NULL (can't be defined, therefore can't be sure it's not a C or a P)?
>
> This is easy enough to fix, I'll change my data load to populate the null
> values with my own code. But still? Have I got the WHY correct?
>
> Thanks for any light someone can shed on this stupid question.
>
> Lisa Koivu
> Oracle Database Monkey Mama
> Fairfield Resorts, Inc.
> 5259 Coconut Creek Parkway
> Ft. Lauderdale, FL, USA 33063
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Koivu, Lisa
> INET: lisa.koivu_at_efairfield.com
>
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  INET: Tim_at_SageLogix.com

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-- 
Author: Pardee, Roy E
  INET: roy.e.pardee_at_lmco.com

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Received on Mon May 06 2002 - 11:53:30 CDT

Original text of this message

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