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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Issue 149: Restrictions on Ordering expression used with Grouping
Date Mon, 19 Dec 2005 19:25:14 GMT
Javadogs,

See JIRA issue JDO-243 http://issues.apache.org/jira/browse/JDO-243? 
page=all
Ordering should have the same restrictions as for the Select clause.  
That is, if grouping is used, only expressions in the Grouping clause  
and aggregate expressions can be in the Ordering clause.
The JDO implementation is not permitted to modify the Select clause,  
the Grouping clause, or the Ordering clause. These are user-visible  
and should not be changed by the implementation.
However, the JDO implementation is required to construct valid SQL if  
the query is being used with a relational datastore. This means that  
the SQL SELECT might need to have expressions added to the user's  
Select clause to include expressions in the Grouping and Ordering  
clauses.
Today in the specification there are restrictions on the expressions  
that can be used in the Select clause if there is a Grouping clause:
<spec 14.6.10>
Only expressions in the Grouping clause and aggregate expressions can  
be in the Select clause.
</spec 14.6.10>
A similar restriction is needed for the Ordering clause.
<proposed>
Only expressions in the Grouping clause and aggregate expressions can  
be in the Ordering clause.
</proposed>

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


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