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Re:

From: Baux David <david(dot)baux(at)inserm(dot)fr>
To:
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re:
Date: 2011-11-16 09:04:30
Message-ID: 4EC37C9E.2040001@inserm.fr (view raw or flat)
Thread:
Lists: pgsql-novice
Right, I am probably wrong. Some other opinion?

d


Le 15/11/11 19:48, jmscott(at)setspace(dot)com a écrit :
> here is a trivial example in 9.1
>
>      jmscott=>  select (1, 2) in (select 1, 2);
>   ?column?
> ----------
>   t
> (1 row)
>
> where the right hand side returns 2 columns, not exactly one column,
> contradicting what the docs say:
>
>>>        The right-hand side is a parenthesized subquery, which must return
>>>        exactly one column.
> seems like a documentation error.  what am i missing?
>
> -j
>
>> well, it seems to me that section 9.20.2 makes sense.
>> http://www.w3schools.com/sql/sql_in.asp
>> I am not sure that you can compare multiple columns such as in:
>>
>> SELECT * FROM Persons WHERE LastName, FirstName IN (SELECT LastName,
>> FirstName FROM OtherPersons);
>>
>> if this is what you mean, at least not using this method, which returns
>> an error.
>>
>> d
>>
>> Le 15/11/11 18:29, jmscott(at)setspace(dot)com a écrit :
>>> I would like clarification on the first paragraph of section 9.20.2 on
>>> the page at
>>>
>>>         http://www.postgresql.org/docs/9.1/static/functions-subquery.html
>>>
>>> regarding the syntax of the 'expression in (subquery)' clause.
>>>
>>> What is meant by
>>>
>>>        The right-hand side is a parenthesized subquery, which must return
>>>        exactly one column.
>>>
>>> ?  Appears to me that the subquery must only contain the same number of
>>> columns as the left hand side, not just 1 column.
>>>
>>> thanks-j
>>>
>>>
>>
>>
>
>


-- 

Baux David
Ingénieur bioinformatique
Groupe neurosensoriel (site web 
<https://194.167.35.160/group/Diagnostic_Usher_fr.html>)
Laboratoire de Génétique Moléculaire - CHU
IURC, Institut Universitaire de Recherche Clinique
UFR Médecine Site NORD UPM/IURC
641 Avenue du Doyen Giraud
34093 MONTPELLIER Cedex 5
*Nouveau numéro:*
04 11 75 98 76

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