[jira] Updated: (DERBY-2459) Ordering on a CASE-expression casues a NullPointerException when using a UNION

["Bryan Pendleton (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-2459?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bryan Pendleton updated DERBY-2459:
-----------------------------------

    Attachment: rejectquery.diff

Attached is rejectquery.diff, a patch proposal. This patch includes
a 2-line change to OrderByColumn to reject the query in the description.
The patch also includes a number of test cases which verify that the
query as stated fails as expected, some other similar queries are
rejected, but also that ORDER BY 2 can be used to order the rows correctly.

Please let me know what you think of this patch.

> Ordering on a CASE-expression casues a NullPointerException when using a UNION
> ------------------------------------------------------------------------------
>
>                 Key: DERBY-2459
>                 URL: https://issues.apache.org/jira/browse/DERBY-2459
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.1.3.1, 10.1.3.2, 10.2.1.6, 10.2.2.0, 10.2.2.1, 10.3.0.0
>         Environment: Java 1.5.0_06-b05 on Linux Ubuntu 5.10. Derby version 10.2.2
>            Reporter: Lars Gråmark
>            Assignee: Bryan Pendleton
>         Attachments: rejectquery.diff
>
>
> When an order by clause involves a CASE-expression as seen below, a NullPointerException is thrown. The error only occurs when two select statements are combined in a union (or union all).
> select t1.id, CASE WHEN t2.value IS NOT NULL THEN t2.value ELSE t1.value END
> from A1 t1
> left outer join B1 t2 ON t2.id = t1.ref
> union all
> select t1.id, CASE WHEN t2.value IS NOT NULL THEN t2.value ELSE t1.value END
> from A2 t1
> left outer join B2 t2 ON t2.id = t1.ref
> order by CASE WHEN t2.value IS NOT NULL THEN t2.value ELSE t1.value END
> --Use the following statement to reproduce the problem:
> create table A1
> (
>    id char(1)
>   ,value int
>   ,ref char(1)
> );
> create table A2
> (
>    id char(1)
>   ,value int
>   ,ref char(1)
> );
> create table B1
> (
>    id char(1)
>   ,value int
> );
> create table B2
> (
>    id char(1)
>   ,value int
> );
> insert into A1 (id, value, ref) values ('a', 12, 'e');
> insert into A1 (id, value, ref) values ('b', 1, null);
> insert into A2 (id, value, ref) values ('c', 3, 'g');
> insert into A2 (id, value, ref) values ('d', 8, null);
> insert into B1 (id, value) values ('e', 4);
> insert into B1 (id, value) values ('f', 2);
> insert into B2 (id, value) values ('g', 5);

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