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https://issues.apache.org/jira/browse/DERBY-4397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12798501#action_12798501
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Bryan Pendleton commented on DERBY-4397:
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Hi Dag,
Did you investigate making the code in OrderByList.sortRequired smarter? It
seems like it's trying
to figure out whether we are ordering by an expression, or by a simple column
reference, and the
VirtualColumnNode confuses it and makes it go into the "sorting by an
expression" scenario.
If you add some code to OrderByList.sortRequired to check for the presence of a
VirtualColumnNode,
and then to fetch the column reference from the virtual colum's result column,
does that help any?
> Allow ORDER BY in subqueries
> ----------------------------
>
> Key: DERBY-4397
> URL: https://issues.apache.org/jira/browse/DERBY-4397
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Dag H. Wanvik
> Assignee: Dag H. Wanvik
> Attachments: derby-4397-1.diff, derby-4397-1.stat, derby-4397-2.diff,
> derby-4397-2.stat, derby-4397-all-subqueries.diff,
> derby-4397-all-subqueries.stat, derby-4397-insert-from-exists.diff,
> derby-4397-insert-from-exists.stat, orderBySpec.html, orderBySpec.html,
> orderBySpec.html, orderBySpec.html, orderBySpec.html
>
>
> SQL 2008 allows ORDER BY to be specified in subqueries. In conjunction with
> OFFSET/FETCH and/or ROW_NUMBER
> meaningful subqueries with row ordering may be formulated. Cf. MySQL's LIMIT
> may be used in subqueries as well.
> Note that OFFSET/FETCH is currently not allowed in subqueries, either.
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