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https://issues.apache.org/jira/browse/DERBY-681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12473226
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Andrew McIntyre commented on DERBY-681:
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I checked Manish's patch and it does fix the original query reported not
working in DERBY-1624. I applied Manish's patch and ran the original query in
the description of DERBY-1624, and it works as expected.
While it would be great if column aliasing worked completely as expected with
all of the queries in derby1624_repro.sql, I would argue that with Manish's
patch committed DERBY-681 and DERBY-1624 should be closed, and a new issue
opened to cover the remaining problems with column aliasing shown in the
derby1624_repro script.
> Eliminate the parser's rewriting of the abstract syntax tree for queries with
> GROUP BY and/or HAVING clauses
> ------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-681
> URL: https://issues.apache.org/jira/browse/DERBY-681
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Rick Hillegas
> Assigned To: Manish Khettry
> Attachments: 681.patch.txt, notes.txt
>
>
> If a query contains a GROUP BY or HAVING clause, the parser rewrites the
> abstract syntax tree, putting aggregates into a subselect and treating the
> HAVING clause as the WHERE clause of a fabricated outer select from the
> subquery. This allows the compiler to re-use some machinery since the HAVING
> clause operates on the grouped result the way that the WHERE clause operates
> on the from list. Unfortunately, this rewriting creates an explosion of
> special cases in the compiler after parsing is done. The rewriting is not
> systematically handled later on in the compiler. This gives rise to defects
> like bug 280. We need to eliminate this special rewriting and handle the
> HAVING clause in a straightforward way. This is not a small bugfix but is a
> medium sized project.
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