Re: Another PDO ?

On 9/10/2012 4:54 PM, Jim Giner wrote:
> On 9/10/2012 11:10 AM, Lester Caine wrote:
>> Jim Giner wrote:
>>> On 9/10/2012 10:49 AM, Bastien Koert wrote:
>>>> On Mon, Sep 10, 2012 at 9:48 AM, Jim Giner
>>>> <[email protected]> wrote:
>>>>> Reading up on the pdostatement class.  Wondering what the intent 
>>>>> of the
>>>>> columnCount function is.  I mean, aren't the number of columns in a
>>>>> result
>>>>> known when you write the query?  Granted, you might have some very
>>>>> complex
>>>>> query that you may not know the number, but for most queries you
>>>>> will know
>>>>> the columns you are expecting.  So - what am I not seeing?
>>>>>
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>>>>
>>>> It might be for those cases where you run a select * from ...
>>>>
>>> But - again - one already knows how many fields are in that table when
>>> one
>>> writes the query...
>>
>> You do not necessarily KNOW how many fields. You know how many fields
>> should be in the version of the database you are coding for, so any
>> difference would flag a problem. Also you may not ACTUALLY have the
>> schema for a database in which case a count of the fields found is
>> useful for further processing those fields.
>>
>> Another area is when you are working with fabricated joined queries
>> where duplicate field names between tables will give a reduced number of
>> final fields in the result.
>>
>> Of cause it IS often better to work with named fields rather than using
>> '*' which does allow better handing of the process anyway.
>>
> I find it difficult to fathom a scenario where I am able to write 
> queries against a db but not have access to the layouts.  Makes it 
> kind of hard to know what I'm going to get back....  but I guess it 
> must occur somewhere since someone decided this function was necessary.
>
You have access to the source table layouts, but it is possible to do 
pivot table type queries where the resultant table bears no resemblance 
to any of the source tables, and the number of columns in your result 
depends on the data.

   Toby


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