| Subject | Re: [firebird-support] Re: Duplicates with LIST function in Fb 2.5.4? |
|---|---|
| Author | Svein Erling Tysvær |
| Post date | 2016-01-11T14:46:13Z |
Thanks Dmitry, learning that the problem is with blobs and not particularly LIST, DISTINCT or UNION helped me realise that the simple workaround is to use cast(list(<field>) as varchar(<size>)) whenever I want to return distinct values of blobs.
Set
2016-01-11 14:31 GMT+01:00 Dmitry Yemanov dimitr@... [firebird-support] <firebird-support@yahoogroups.com>:
11.01.2016 11:49, Svein Erling Tysvær wrote:
> Hi, I'm puzzled by two queries returning duplicate rows:
>
> 1)
> SELECT LIST('Hi') FROM RDB$DATABASE
> UNION
> SELECT LIST('Hi') FROM RDB$DATABASE
>
> 2)
> WITH TMP(DuplicateRows) AS
> (SELECT LIST('Hi') FROM RDB$DATABASE
> UNION
> SELECT LIST('Hi') FROM RDB$DATABASE)
> SELECT DISTINCT DuplicateRows
> FROM TMP
LIST returns a blob. DISTINCT doesn't work with blobs properly, it
operates with blob ids (that are surely distinct) instead. See:
http://tracker.firebirdsql.org/browse/CORE-1345
http://tracker.firebirdsql.org/browse/CORE-1530
Dmitry
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Posted by: Dmitry Yemanov <dimitr@...>
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