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https://issues.apache.org/jira/browse/DERBY-4397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12763309#action_12763309
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Dag H. Wanvik commented on DERBY-4397:
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Thanks for looking at this, Knut, Rick.
@Knut
Re 1), I can't see that ORDER BY should be allowed before a UNION without a (),
can you explain how you reach that conclusion? It seems to me that what comes
before the UNION must eventually come from a <query primary> which is either a
table name or a (parenthesized) subquery..
2) I hope so, I agree that in an INSERT context, an ORDER BY in the subquery
should not be ignored in the presence of identity columns.
3) Yes that is correct, I was thinking of the case where the ORDER BY is inside
a subquery and the containing query contains a window. Btw, hat case may be
covered by an ORDER BY inside the window specification (equivalently?) when we
support that.
4) I am not aware of any such backwards-compatibility issues at this point. I
added this as a reminder to self to check it ;-)
@Rick
Good point about the user guide for INSERT. Will add a note on that.
> 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
> Attachments: 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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