[DB-SIG] Please some clarification of DB Spec 2.0

[M.-A. Lemburg]

Jose de Leon wrote:
> 
> Hello!
> 
> I apologize if I ask questions asked many times before.  I'd search the
> archives but my connetion to the python site is VERY slow.
> 
> First:
> a) I'm new to python.
> b) I'm new to the Python DB Spec 2.0.
> 
> I'm creating a database module interface.  But before I code it python.  I'm
> trying to code it in C++, a language I know much better.  I then intend to
> use SWIG to convert the C++ code to python.  Possibly by creating a python
> shadow wrapper.
> 
> One of the items I need clarification on is "sequence".
> 
> What exactly is a sequence and how can I relate that to a C++ datatype?
> >From what I can gather from "Programming Python" by O'Reilly is that it is a
> string with delimiters.  Or it could be an array?

Its a conglomeration of elements which can be indexed using integers.
Python lists and tuples are examples for sequences. C arrays also
fit this definition. Basically, they have to provide a length and
a method which allows indexing all elements starting from index 0
to length - 1.
 
> The specific specification from the DB Spec 2.0 that confuses me is the
> description for a the "description" method of a Cursor object.
> 
> It explains:
> 
> description
>     This read-only attribute is a sequence of 7-item sequences....etc.

This normal refers to a tuple of tuples, one 7-tuple (a tuple
of length 7) for each column in the result set.
 
> Likewise, the description for "fetchone()" method also confuses me on how to
> return the data.  Should the data be returned in an array?

It should return a sequence, such as a tuple corresponding to
a row in the result set, with each element representing a column
entry.

Hope that helps,
-- 
Marc-Andre Lemburg
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