[DB-SIG] PEP249 - Proposed change to DB-API 2.0

[M.-A. Lemburg]

> [Making the DB API interface handle multiple paramstyles]
> 
> > Sybase only supports the ? place holder.
> >
> > I am not sure how feasible this is, but maybe a (simple) SQL parser
> > could be used to support any placeholder style which would then be
> > transformed into the native style to interface with the database API.
> 
> That would work for me too. Frankly, I dont see why the API should not
> support /all/ styles. The API writer codes the style the backend database
> most easily supports, then helper functions (supplied by the python-core
> libraries, for example) turn all the other styles into that style for you.
> 
> The /user/ of the DB-API should not have to care what the 'native' style
> is, since there is a deterministic conversion between all styles (I
> think).
> 
> However it is done, I should not have to rewrite code just because I slot
> in a different API.

That's easy for you to say ;-) However, your small benefit will cost a 
lot of module writers a lot of work and sometimes it may even
not be possible getting this right.

To support all the different styles, the module writer would have
to parse the SQL statement to figure out how to map the paramstyle
used in there to the native one. Writing an SQL parser is not
necessarily possible though, since there are so many different
SQL variations in use out there. I'm not even talking about quoting
rules here ;-)

If you really care about being able to change database interfaces,
then you'll have to write an abstraction for your interface anyway,
so why put the burden on the DB API writer here ? (This only makes
it harder for interface writers to come up with code which can
be considered DB API compatible.)

-- 
Marc-Andre Lemburg
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