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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3634) Cannot use row_number() in ORDER BY clause
Date Thu, 15 Oct 2009 11:36:31 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3634?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12766028#action_12766028
] 

Knut Anders Hatlen commented on DERBY-3634:
-------------------------------------------

Thanks Dag, it looks like the problems I found in the previous patch have been fixed. Noticed
another problem with this query (inspired by DERBY-4391):

ij> create table t(x int unique, y int);
0 rows inserted/updated/deleted
ij> insert into t values (1,2);
1 row inserted/updated/deleted
ij> select * from t where x > (select row_number() over () from sysibm.sysdummy1 union
select 1-row_number() over () from sysibm.sysdummy1 where 1=0);
ERROR 21000: Scalar subquery is only allowed to return a single row.

But the scalar subquery does return a single row:

ij> select row_number() over () from sysibm.sysdummy1 union select 1-row_number() over
() from sysibm.sysdummy1 where 1=0;
1                   
--------------------
1                   

1 row selected

> 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-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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