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https://issues.apache.org/jira/browse/DERBY-2351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12505472
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Bryan Pendleton commented on DERBY-2351:
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The SQL Standard appears to agree with the conclusion that queries such as
those Yip has constructed should be rejected as invalid. Here's a brief
synopsis of why I think the standard says this:
- Section 14.1 (2003 standard) covers DECLARE CURSOR.
- Syntax Rule 18 covers the ORDER BY clause
- Syntax Rule 18.d.i covers the case in which the ORDER BY clause contains a
sort key that contains a column reference to a column that is not a column of
the result of the query expression
- Syntax Rule 18.d.i.9.B.II states:
QS shall not specify the <set quantifier> DISTINCT or directly contain one or
more <set function specification>s.
So I propose to modify the ORDER BY column checking so that it rejects such
queries.
> ORDER BY with expression with distinct in the select list returns incorrect
> result
> ----------------------------------------------------------------------------------
>
> Key: DERBY-2351
> URL: https://issues.apache.org/jira/browse/DERBY-2351
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.2.2.0, 10.3.0.0
> Environment: Any
> Reporter: Yip Ng
> Assignee: Bryan Pendleton
> Attachments: reproTests.diff
>
>
> When distinct is in the select list and the query has order by with
> expression, the resultset produced contains an additional column.
> ij> create table t1 (c1 int, c2 varchar(10))
> 0 rows inserted/updated/deleted
> ij> insert into t1 values (1,'a'),(2,'b'),(3,'c');
> 3 rows inserted/updated/deleted
> select distinct c1, c2 from t1 order by c1;
> C1 |C2
> ----------------------
> 1 |a
> 2 |b
> 3 |c
> 3 rows selected
> ij> select distinct c1, c2 from t1 order by c1+1;
> C1 |C2 |3 <=====returns 3
> columns, incorrect result returned
> ----------------------------------
> 1 |a |2
> 2 |b |3
> 3 |c |4
> 3 rows selected
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