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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2351) ORDER BY with expression with distinct in the select list returns incorrect result
Date Thu, 06 Mar 2008 14:54:58 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12575727#action_12575727
] 

Bryan Pendleton commented on DERBY-2351:
----------------------------------------

I suppose one last try would be:
 - unqualified ORDER BY reference: bind first to alias, then to column in (any) underlying
table
 - qualified ORDER BY reference: bind first to column in corresponding underlying table, then
to alias

That would make the nasty query from synonym.sql work, I suppose,
but it doesn't feel like very pleasant code to need to write. If I could
start from scratch I'd prefer to make all these ambiguous cases be
errors, as I suspect that users don't really want to relabel one column
with an identical name to another column; they'd prefer to always choose
unique alias names and have no ambiguity about their 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: 10.2.1.6, 10.2.2.0, 10.3.1.4
>         Environment: Any
>            Reporter: Yip Ng
>            Assignee: Bryan Pendleton
>             Fix For: 10.3.2.2, 10.4.0.0
>
>         Attachments: d2351_aliasing.diff, d2351_aliasing.diff, d2351_aliasing_checkQualifiedName.diff,
derby_2351.diff, derby_2351_v2.diff, 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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