RE: Any known problems using NOT IN ?

From: Charu Joshi <joshic_at_mahindrabt.com>
Date: Wed, 17 Dec 2003 21:39:26 -0800
Message-ID: <F001.005DA355.20031217213926@fatcity.com>

Siddharth,

The NOT IN query fails to return rows, if the inner sub-query returns NULL values. It is always recommended to use the NOT EXISTS clause, unless you are sure that the inner query will not return any NULLs.

Regards,

Charu.

-----Original Message-----
From: ml-errors@fatcity.com [mailto:ml-errors@fatcity.com]On Behalf Of Siddharth Haldankar
Sent: 18 December 2003 10:54
To: Multiple recipients of list ORACLE-L
Subject: Any known problems using NOT IN ?

Hi Gurus,

I have a problem using NOT IN clause in Oracle. However using NOT EXISTS, gives me the right output. Are there any known limitations.

This query selects from the master records wherein child records are not active.

select * from ct_software_release csr where

csr.class         = 'NS'

AND    csr.active_flag   = 'Y'

AND    csr.os_id_pk not IN

(SELECT crs.os_id_fk1 FROM CT_ROADMAP_SOFTWARE crs

        WHERE crs.active_flag = 'Y');

The sub-query in the above case gives 1800 rows. The above query fails to give any rows.



select * from ct_software_release csr where

csr.class         = 'NS'

AND    csr.active_flag   = 'Y'

AND    NOT EXISTS

        (SELECT 1 FROM CT_ROADMAP_SOFTWARE crs

        WHERE crs.os_id_fk1 = csr.os_id_pk

                                AND crs.active_flag = 'Y');

This above query works fine.

Thanks

Siddharth Haldankar

Zensar Technologies Ltd.

Cisco Systems Inc.

(Offshore Development Center)

# : 091 020 4128394

shaldank@cisco.com

s.haldankar@zensar.com

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Author: Charu Joshi
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Received on Wed Dec 17 2003 - 23:39:26 CST