Re: something appears to be funny with ROWNUM

From: Tanel Poder <tanel.poder.003_at_mail.ee>
Date: Wed, 09 Jul 2003 01:37:55 -0700
Message-ID: <F001.005C3F15.20030709012924@fatcity.com>

Hi!

Put it that way that since ROWNUM is a pseudocolumn and a reserved word, you shouldn't include ROWNUM in your outer query if you want to limit results from your subquery. The correct example would be:

select r, object_id
from (select rownum r, object_id

      from dba_objects
      where rownum <= 600

)
where r >= 500
/

Or if you definitely want rownum to be one name of your columns in resultset, then use double quotation marks to enclose reserved word(s):

select r "ROWNUM", object_id
from (select rownum r, object_id

      from dba_objects
      where rownum <= 600

)
where r >= 500
/

Tanel.

Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Wednesday, July 09, 2003 5:39 AM

>
> My query below is probably flawed... I just remembered you would have to
> alias rownum...
>
> select inner_row as rownum, gender
> from (select rownum as inner_row, gender
> from emp2 where rownum <= 600)
> where rownum >= 500;
>
> Regards,
> Mark.
>
> Ryan did a good job of explaining the use of rownum - better than my
> attempt.
>
>
>
>
> Mark Richard
> To:
[EMAIL PROTECTED]
> 09/07/2003 11:37 cc:
> Subject: Re: something
appears to be funny with ROWNUM(Document link: Mark Richard)
>

>
>
>
> ROWNUM has to start from 1 - If you never select a row then rownum can't
> increase. You have to assign rownums and then filter them out later,
> usually using a subquery.
>
> The solution to your specific query below would be something like:
>
> select rownum, gender
> from (select rownum, gender
> from emp2
> where rownum <= 600
> )
> where rownum >= 500;
>
> The emails I sent earlier for your other problem are based around the fact
> that rownum will restart from 1 during each iteration. You possibly don't
> understand rownum properly - it is a unique number assigned to a specific
> result set, not the rows existing in the underlying table. It must start
> from 1 each time and therefore where clauses can only test some conditions
> like "rownum = 1" (get a single row), "rownum <= x" (get up to x rows).
>
>
>
>
>
> MaryAnn Atkinson
> <[EMAIL PROTECTED] To: Multiple
recipients of list ORACLE-L <[EMAIL PROTECTED]>
> .com> cc:
> Sent by: Subject: something appears
to be funny with ROWNUM
> [EMAIL PROTECTED]
> .com
>
>
> 09/07/2003 12:14
> Please respond to
> ORACLE-L
>
>
>
>
>
>
> 1. this first query gave me 600 lines of output.
>
> SELECT Rownum, Gender
> FROM EMP2
> WHERE ROWNUM <= 600;
>
> ------------
>
> 2. this one right here told me no rows selected...
>
> SELECT Rownum, Gender
> FROM EMP2
> WHERE ROWNUM BETWEEN 500 and 600;
>
> I dont get it... something is funny with ROWNUM...
>
>
> Any ideas?
> thx
> maa
>
> __________________________________
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>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Mark Richard
> INET: [EMAIL PROTECTED]
>
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> San Diego, California -- Mailing list and web hosting services
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Tanel Poder
  INET: [EMAIL PROTECTED]

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Received on Wed Jul 09 2003 - 03:37:55 CDT