[DB-SIG] Controlling return types for DB APIs

Michael Bayer mike_mp at zzzcomputing.com
Wed Apr 18 02:50:32 CEST 2007

On Apr 17, 2007, at 4:12 PM, Federico Di Gregorio wrote:

> The Python->SQL part is perfect for adaptation and, for example,  
> psycopg
> has a micro-protocols implementation to help with the adaptation of  
> any
> Python object into a valid ISQLQuote one. Why two different systems?
> Because transating Python to SQL and SQL to Python are two very
> different operations, IMHO.

they are different operations, but their semantics are mirror images  
of one another.   it follows very closely if you are binding a  
datetime object to a bind param which is in a SQL expression being  
compared against a particular column, that the rules which convert  
the datetime to a SQL value are the same rules in reverse that would  
convert the selection of that column in the result.  this is why i  
think the "type" of a column, both its bind param adaptation as well  
as its result row adaptation, can be expressed by the same rule  
object in most cases.  and I know it works since this is how  
sqlalchemy has been doing it for quite a while now.

More information about the DB-SIG mailing list