On 17.12.2014 14:50, SF Markus Elfring wrote: >> How about: >> >> """ >> The prepared operation is only available until the next call to >> one of the .execute*() methods or another call to the .prepare() >> method using a different command string than the one used for >> preparing the previous operation. >> """ > > Can the prepare() method return a handle for a SQL statement?
The proposal says: """ Return values are not defined. """ which we traditionally use on the DB-API to mean: the method may return something, but whatever it returns is database module specific and not something to rely on on general. > Will prepared SQL statements be mapped to a specific class hierarchy > in Python? Not sure what you mean. Having prepared a statement only means that the cursor has run it by the database to build an access plan and, as a side-effect, has most likely run the parser on it. In practice, a database module may implement this method as mostly no-op operation. Some databases don't support prepared statements or don't work well in this mode, other may not run the parser and thus not necessarily raise errors during the call (only in the subsequent .execute()). The most likely case, however, is that you can use .prepare() to check for errors (and hopefully, without causing the transaction to be canceled, in case there are errors). >> It is possible to open a few cursors, prepare frequently >> used statements on them and them make them accessible via >> a cursor pool. This works well (I know since I've implemented >> such a logic some 14-15 years ago in a large application). > > How should the application programming interface look like > in Python for this use case? Depends on the application and what you want to achieve. There's no general answer to this. >> The DB-API standard extensions were added to address proliferation >> of such additions. If possible, the database modules should try >> to standardize on these extensions, which is why discussions such >> as these are useful. > > Are there more software improvements in a waiting queue? There are a few extensions that we've been discussing off and on. The cursor.prepare() method is one of the more recent ones. One of these days, I'll have to go through the archives and collect a list :-) -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, Dec 17 2014) >>> Python Projects, Coaching and Consulting ... http://www.egenix.com/ >>> mxODBC Plone/Zope Database Adapter ... http://zope.egenix.com/ >>> mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/ ________________________________________________________________________ 2014-12-11: Released mxODBC Plone/Zope DA 2.2.0 http://egenix.com/go67 ::::: Try our mxODBC.Connect Python Database Interface for free ! :::::: eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 http://www.egenix.com/company/contact/ _______________________________________________ DB-SIG maillist - DB-SIG@python.org https://mail.python.org/mailman/listinfo/db-sig
