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From "Muhammad Gelbana (JIRA)" <j...@apache.org>
Subject [jira] [Created] (JDO-721) Specifying NULL elements positioning in ordered columns
Date Sun, 28 Apr 2013 16:00:17 GMT
Muhammad Gelbana created JDO-721:
------------------------------------

             Summary: 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
            Priority: Minor


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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