Re: can someone explain confusing array indexing nomenclature

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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