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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5954) NPE in SELECT involving subselects and windows functions
Date Fri, 19 Oct 2012 14:08:12 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13480040#comment-13480040

Dag H. Wanvik commented on DERBY-5954:

Uploading patch derby-5954, which is a simple one-line patch that makes the row_number variants
work, i.e.
it will work as "well" as the table select with similar nesting/correlated query above. I'll
address the "0" instead of null in another issue.

The issue was the following: when looking for in-line window definitions in the select list,
the visitor looked to deep: it should not move into subqueries in the select list. This error
caused the query tree to become seriously garbled, hence the NPE and the assert seen.

Still need to add a JUnit test, so not for commit yet.
> NPE in SELECT involving subselects and windows functions
> --------------------------------------------------------
>                 Key: DERBY-5954
>                 URL: https://issues.apache.org/jira/browse/DERBY-5954
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions:
>            Reporter: Rick Hillegas
> A user reports and I have verified an NPE on the following SELECT:
> connect 'jdbc:derby:memory:db;create=true';
> create table blah ( a int );
> insert into blah values (1), (2), (3), (4), (5), (6), (7);
> SELECT rn, (SELECT rn FROM (SELECT row_number() over() rn FROM blah ) as T2
> where T2.rn = T1.rn+1) rn2
> FROM (SELECT row_number() over() rn from blah) as T1;

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