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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3634) Cannot use row_number() in ORDER BY clause
Date Fri, 16 Oct 2009 00:26:31 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3634?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12766346#action_12766346
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Dag H. Wanvik commented on DERBY-3634:
--------------------------------------

Yes, that's how I read it, too (no col.ref -> rejection). A window function is explicitly
allowed inside an ORDER BY clause, though, cf. SQL 2003:2, section 4.15.3 "Window functions":

"Window functions may only appear in the <select list> of a <query specification>
or <select statement: single row>, or the <order by clause> of a simple table
query."

But Derby is more lenient, allowing <sort key>s without column references, so I think
ROW_NUMBER doesn't introduce anything new in this respect, as you found in DERBY-4406 ("ORDER
BY RANDOM()")

> Cannot use row_number() in ORDER BY clause
> ------------------------------------------
>
>                 Key: DERBY-3634
>                 URL: https://issues.apache.org/jira/browse/DERBY-3634
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.4.1.3
>            Reporter: Rick Hillegas
>            Assignee: Dag H. Wanvik
>         Attachments: derby-3634-a.diff, derby-3634-a.stat, derby-3634-a.txt, derby-3634-b.diff,
derby-3634-b.stat, derby-3634-c.diff, derby-3634-c.stat, derby-3634-newimpl-1.diff, derby-3634-newimpl-1.stat,
derby-3634-newimpl-1.txt, derby-3634-newimpl-2.diff, derby-3634-newimpl-2.stat, derby-3634-newimpl-3.diff,
derby-3634-newimpl-3.stat, derby-3634-newimpl-4.diff, derby-3634-newimpl-4.stat, derby-3634-remove-2.diff,
derby-3634-remove-2.stat, derby-3634-remove.diff, derby-3634-remove.stat
>
>
> The following query works correctly:
> select abs(a), row_number() over ()
> from t
> where a > 100 and a < 111
> order by abs(a)
> I expected the following query to also work, but it raised an exception:
> select abs(a), row_number() over ()
> from t
> where a > 100 and a < 111
> order by row_number() over ()
> This is the error I saw: "ERROR 42X01: Syntax error: Encountered "over" at line 5, column
23".
> Here are the reasons why I think that this syntax is supposed to be supported:
> According to my reading of the 2003 SQL spec, the ORDER BY clause should be able to sort
on any expression in the SELECT list. That includes OLAP expressions. I believe this is so
because, according to part 2, section 10.10 (<sort specification>), a <sort key>
can be any <value expression> and if you follow the grammar for <value expression>,
it can resolve to be a <value expression primary> (see section 6.3), which can in turn
resolve to be a <window function>. This reasoning is supported by tracing the hotlinks
on the following page which lays out the SQL 2003 BNF: http://savage.net.au/SQL/sql-2003-2.bnf.html
This interpretation is further supported by the example of an ORDER BY clause referencing
an OLAP expression which is provided on page 23 of the introduction to OLAP written by Fred
Zemke, Krishna Kulkarni, Andy Witkowski, and Bob Lyle: www.cse.iitb.ac.in/dbms/Data/Papers-Other/SQL1999/OLAP-99-154r2.pdf

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