From: chrisj <chrisj.wood@sympatico.ca>
To: pgsql-sql@postgresql.org
Subject: Re: can someone explain confusing array indexing nomenclature
Date: Fri, 16 Feb 2007 10:35:13 -0800 (PST)
Message-ID: <9009934.post@talk.nabble.com> (raw)
In-Reply-To: <200702161034.43399.achill@matrix.gatewaynet.com>
References: <8971770.post@talk.nabble.com>
<200702151224.12455.achill@matrix.gatewaynet.com>
<8989242.post@talk.nabble.com>
<200702161034.43399.achill@matrix.gatewaynet.com>
I am quite sure the [2] is not discarded, easy enough to test but I don't
have access to PG at the moment.
Achilleas Mantzios wrote:
>
> Στις Πέμπτη 15 Φεβρουάριος 2007 18:55, ο/η chrisj έγραψε:
>> Thanks Achilleas,
>>
>> I see what you are saying, but if we consider just the index "[2]" for a
>> moment,
>> it means something different depending upon the context (in one case it
>> means "2" and in the other case it means "1:2") and the context is
>> determined by the format of indexes on other dimensions.
>>
>> I believe I understand....but incredibly confusing.
>>
>
> Now that i think about it again, i speculate that the [2] is discarded.
>
>> - chris
>>
>> Achilleas Mantzios wrote:
>> > Ξ£ΟΞΉΟ Ξ�Ξ΅ΟΞ¬ΟΟΞ· 14 ΦΡβΟΞΏΟ Ξ¬ΟΞΉΞΏΟ 2007 21:31, ΞΏ/Ξ·
>> chrisj
> ΞΞ³ΟΞ±ΟΞ΅:
>> >> given the following table:
>> >>
>> >> protocal2=> select * from sal_emp ;
>> >> name | pay_by_quarter | schedule
>> >>
>> -------+---------------------------+------------------------------------
>> >>--- ---- Bill | {10000,10000,10000,10000} |
>> >> {{meeting,lunch},{training,presentation}}
>> >> Carol | {20000,25000,25000,25000} |
>> >> {{breakfast,consulting},{meeting,lunch}}
>> >> (2 rows)
>> >>
>> >> why do the following two queries yield different results??
>> >>
>> >> protocal2=> SELECT schedule[1][2] FROM sal_emp WHERE name = 'Bill';
>> >> schedule
>> >> ----------
>> >> lunch
>> >> (1 row)
>> >>
>> >> protocal2=> SELECT schedule[1:1][2] FROM sal_emp WHERE name = 'Bill';
>> >> schedule
>> >> -------------------
>> >> {{meeting,lunch}}
>> >> (1 row)
>> >
>> > The [n:m] notation denotes a slice of the array (not element).
>> > So schedule[1][2] is the Array element on 2nd col of 1st row,
>> > while schedule[1:1][2] could mean
>> > the second row of the subarray schedule[1:1][1:2].
>> > So these two are foundamentally different things.
>> > In my 7.4 even if you gave
>> > SELECT schedule[1:1][888] FROM sal_emp WHERE name = 'Bill';
>> > you would still get {{meeting,lunch}} as a result.
>> > (Right or wrong is another story).
>> > Anyway the first time you query for a "text",
>> > the second time you query for a "text[]", so you should expect
>> > different results.
>> > --
>> > Achilleas Mantzios
>> >
>> > ---------------------------(end of
>> broadcast)---------------------------
>> > TIP 3: Have you checked our extensive FAQ?
>> >
>> > http://www.postgresql.org/docs/faq
>
> --
> Achilleas Mantzios
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq
>
>
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To: pgsql-sql@postgresql.org
Cc: chrisj.wood@sympatico.ca
Subject: Re: can someone explain confusing array indexing nomenclature
In-Reply-To: <9009934.post@talk.nabble.com>
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