Re: storing survey answers of different data types

Joe Thurbon wrote:

> On Sun, 26 Apr 2009 11:03:17 +1000, Bob Badour
> <bbadour_at_pei.sympatico.ca> wrote:
>

>> Joe Thurbon wrote:
>>
>>> On Sun, 26 Apr 2009 03:35:57 +1000, Bob Badour  
>>> <bbadour_at_pei.sympatico.ca>  wrote:
>>>
>>>> Joe Thurbon wrote:
>>>>
>>>>> On Sat, 25 Apr 2009 10:57:16 +1000, Bob Badour   
>>>>> <bbadour_at_pei.sympatico.ca>  wrote:
>>>>>
>>>>>> Joe Thurbon wrote:
>>>>>>
>>>>>>> On Fri, 24 Apr 2009 14:41:12 +1000, Bob Badour    
>>>>>>> <bbadour_at_pei.sympatico.ca>  wrote:
>>>>>>>
>>>>>>>> paul c wrote:
>>>>>>>>
>>>>>>>>> Bob Badour wrote:
>>>>>>>>>
>>>>>>>>>> paul c wrote:
>>>>>>>>>>
>>>>>>>>>>> Bob Badour wrote:
>>>>>>>>>>>
>>>>>>>>>>>> Joe Thurbon wrote:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> ...
>>>>>>>>>>>
>>>>>>>>>>>>> Just wondering, if one of the requirements for a system  
>>>>>>>>>>>>> included
>>>>>>>>>>>>> something like 'Be able to list all questionnaires', would
>>>>>>>>>>>>> you still consider one-table-per-questionairre a 
>>>>>>>>>>>>> reasonable    design?
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Absolutely. It's a simple query from the system catalog.
>>>
>>>  [...]
>>>
>>>>>  Take a table called "Questionnaires", with a single column, 
>>>>> called    "TableName".
>>>>>  For example, the table Questionnaires might contain
>>>>>  Questonnaires  TableName
>>>>> =============-------------------
>>>>>                Customer Survey
>>>>>                Staff Satisfaction Survey
>>>
>>>   [...]
>>>
>>>>>  Customer Survey   A1    A2    A3.....
>>>>> ===============---------------------------
>>>>>  and
>>>>>  Staff Satisfaction Survey   Aa   Ab   Ac
>>>>> =========================---------------------
>>>
>>>
>>>>>  My point above is that is it impossible to encode the constraint  
>>>>> that  the  values in the Questionnaires table correspond to 
>>>>> tables,  and that  those  tables must exist in the database. 
>>>>> (Actually, it's  more my  contention than  my point - I'm not 
>>>>> actually sure that it's  true).
>>>>
>>>>
>>>> Impossible? It's a simple foreign key reference to the system catalog.
>>>>
>>>  This just seems to shift the issue to the system catalog. Doesn't 
>>> the   system catalog make assertions about which tables exists, but 
>>> those   assertions are not modelled as constraints?
>>>  In other words, I think that the system catalog is a bit of a red  
>>> herring.  I had intended that the Questionnaire table in the example  
>>> above take its  place entirely.
>>
>> The Questionnaire table in the example above says nothing about the  
>> columns of the tables.

I disagree regarding the unrelatedness.

>>>>>>>  "What are all the answers to all of the questions to all of 
>>>>>>> the     questionnaires?"
>>>>>>
>>>>>> The contents of the database.
>>>>>
>>>>>  I don't think so.
>>>>
>>>> It is quite clearly and quite explicitly the answer to the 
>>>> question.  If  you think otherwise, I am at a loss.
>>>
>>>  You snipped the second sentence in my reply. It said that (perhaps   
>>> unclearly)
>>> (1) the Questionnaires table (or system catalog, or equivalent)
>>>     is in the database, and must be there to list the questionnaires
>>> (2) the system catalog is not the answer to a question in a  
>>> questionnaire,
>>> (3) 'the contents of the database' is therefore not the answer to 
>>> the   query,
>>>     because it contains too much information.
>>
>> I fail to see the point. The contents of the database are the answers 
>> to  all the questionnaires regardless what else might be in there.

No. There is nothing unsound about the answer.

>>>>>>> Maybe my question (the one I didn't manage to ask upthread)  
>>>>>>> doesn't   have a  meaningful and consise answer. Maybe the 
>>>>>>> question  is just  "How  to I design  a  schema that makes the 
>>>>>>> right  tradeoffs for my   requirements?" But there  seems to be 
>>>>>>> an issue  with the approach  above,  because it makes everything  
>>>>>>> 2nd order,  and hence not  expressible as  relations. (How's that 
>>>>>>> for an   assertion without  proof?)
>>>>>>
>>>>>> Absurd.
>>>>>
>>>>>  Which bit?
>>>>
>>>> The assertion without proof and the idea that a 1st order logic  
>>>> system  is somehow magically 2nd order.
>>>
>>>  I thought it was straightforward. I'll list my reasoning here,
>>>  (1) Each relation R is a predicate
>>> (2) Each tuple in the relation R(v1, ..., vn) is a ground instance
>>>     of that predicate
>>> (3) A system catalog is a predicate which contains unground instances
>>>     of other predicates.
>>> (4) That's second order
>>
>> 3 is dodgy. A system catalog is just a bunch of relations a la 1) and 2).

No, I am not saying that. Obviously, any relation in the system catalog is a predicate.

>>> I think that the reasoning is sound, but am happy to be shown  
>>> otherwise. I don't think I've entered a thread in comp.object 
>>> without  learning  something.
>>
>> I suggest you probably learned less than you thought.