From: chrisj <chrisj.wood@sympatico.ca>
To: pgsql-sql@postgresql.org
Subject: Re: can someone explain confusing array indexing nomenclature
Date: Thu, 15 Feb 2007 08:55:58 -0800 (PST)
Message-ID: <8989242.post@talk.nabble.com> (raw)
In-Reply-To: <200702151224.12455.achill@matrix.gatewaynet.com>
References: <8971770.post@talk.nabble.com>
<200702151224.12455.achill@matrix.gatewaynet.com>
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.
- chris
Achilleas Mantzios wrote:
>
> Στις Τετάρτη 14 Φεβρουάριος 2007 21:31, ο/η chrisj έγραψε:
>> 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
>
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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: <8989242.post@talk.nabble.com>
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