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https://issues.apache.org/jira/browse/DERBY-6008?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13511484#comment-13511484
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Knut Anders Hatlen commented on DERBY-6008:
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I tested some queries in ij, and the patch seems to do the right thing.
The syntax check in the set operations seems to be a little stricter than in a
top-level query, as we accept
VALUES 3, 2, 1 ORDER BY 1
but not
(VALUES 3, 2, 1 ORDER BY 1) UNION VALUES 4
If the former is valid SQL, we should probably allow the latter too, but I
haven't checked what the standard says.
Apart from that, it looks fine to me.
And a tiny nit, feel free to ignore: In the error checking added to
nonJoinQueryPrimary(), the two inner if statement levels could probably be
flattened to a single level, which might make it a little clearer.
> Allow ORDER BY and FETCH/OFFSET in set operands
> -----------------------------------------------
>
> Key: DERBY-6008
> URL: https://issues.apache.org/jira/browse/DERBY-6008
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Dag H. Wanvik
> Assignee: Dag H. Wanvik
> Attachments: derby-6008-a.diff, derby-6008-a.stat, derby-6008-b.diff,
> derby-6008-b.stat
>
>
> Currently, Derby doesn't allow ORDER BY nested in a set operand, e.g. in the
> following construct:
> (select i from t1 order by j offset 1 row) union
> (select i from t2 order by j desc offset 2 rows)
> This is allowed by the standard, as far as I can understand, cf. this quote
> from section 7.12 in SQL 2011:
> <query expression body> ::=
> <query term>
> | <query expression body> UNION [ ALL | DISTINCT ]
> [ <corresponding spec> ] <query term>
> | <query expression body> EXCEPT [ ALL | DISTINCT ]
> [ <corresponding spec> ] <query term>
> <query term> ::=
> <query primary>
> | <query term> INTERSECT [ ALL | DISTINCT ]
> [ <corresponding spec> ] <query primary>
> <query primary> ::=
> <simple table>
> | <left paren> <query expression body>
> [ <order by clause> ] [ <result offset clause> ] [ <fetch first clause>
> ] <right paren>
> I.e. the left paren chooses the second alternative in the production for
> <query primary>.
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