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Posted to jdo-dev@db.apache.org by "Michael Bouschen (JIRA)" <ji...@apache.org> on 2014/09/12 18:42:33 UTC
[jira] [Assigned] (JDO-721) Specifying NULL elements positioning in
ordered columns
[ https://issues.apache.org/jira/browse/JDO-721?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michael Bouschen reassigned JDO-721:
------------------------------------
Assignee: Michael Bouschen
> Specifying NULL elements positioning in ordered columns
> -------------------------------------------------------
>
> Key: JDO-721
> URL: https://issues.apache.org/jira/browse/JDO-721
> Project: JDO
> Issue Type: Improvement
> Components: specification
> Affects Versions: JDO 3 update 1 (3.0.1)
> Reporter: Muhammad Gelbana
> Assignee: Michael Bouschen
> Priority: Minor
> Labels: jdoql
> Fix For: JDO 3.1
>
>
> I don't know about other RDBMS but in MySQL ordering, it's possible to specify whether NULL column fields are placed in the beginning or at the end of the ordering, i.e.:
> ORDER BY `values_column` IS NULL DESC
> [values_column]
> NULL
> NULL
> value1
> value2
> value3
> or the other way around (ORDER BY `values_column` IS NULL ASC):
> [values_column]
> value1
> value2
> value3
> NULL
> NULL
> I checked JDO 3 specification and found that JDOQL's ordering specification doesn't support specifying NULL values handling:
> ------------------------------------------------------------------------------
> 26.7 Ordering Specification
> This section describes the syntax of the setOrdering argument.
> OrderingClause:
> OrderingSpecs ,opt
> OrderingSpecs:
> OrderingSpec
> OrderingSpecs , OrderingSpec
> OrderingSpec:
> Expression Ascending
> Expression Descending
> Ascending: one of
> asc ascending
> Descending: one of
> desc descending
> Please note, as a usability feature OrderingClause supports an optional trailing comma.
> ------------------------------------------------------------------------------
> Thank you for your time and efforts.
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