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Fabian Fagerholm
fabbe at paniq.net
Mon Sep 9 12:00:11 EST 2002
On Mon, 2002-09-09 at 05:28, Mark Nielsen wrote: > In Perl, the core DBI module takes care of all database connections which > use DBI if you also use Apache DBI. > I was thinking, there should be a standard way of doing it rather than > relying on each database author. Hence DBAPI. http://www.python.org/topics/database/DatabaseAPI-2.0.html > There should be a way to do it in Python irrelevant of which database > connection you use. We would just need a way to make the database > connections global variables which don't die. I agree that it would be useful to be able to keep any such objects between browser requests. Perhaps there would be a way to place the connection objects in the global namespace of each mod_python subinterpreter so that they would continue to exist until the subinterpreter dies? But this is a separate issue from the "generic database access" issue. > So, I guess, I probably will have to make up a way to do it. > I use MySQL, PostgreSQL, and Oracle, and also DBM, so I need one way > for all database connections. Even the three SQL-capable ones have slight variations in the SQL syntax which makes it hard to find a good lowest common denominator that could be accepted as "standard". I would write an abstract class that defines the behavior you need and then four subclasses to implement that behavior for the four database back-ends you mention. The interface to your application would be your own, and the interface to each database would make use of DBAPI 2.0 modules specific to each database. Making the abstract class "standard" makes little sense since it's probably not very large or complicated, and it's often quite specific to your application. I also fail to see how Perl DBI solves certain issues. For example, if you use Perl DBI and write an application that relies on transactional capabilities of the database, and you move to a database without transactional capabilities (MySQL with MyISAM tables, for instance) then you'll have to adapt your code. Also, in every single Perl DBI example I've seen, there's SQL embedded in the code. I probably don't understand DBI but it seems to me that this makes it essentially impossible to write code for, say, an Oracle database that makes use of Oracle-specific features, and then run the same code with a MySQL database as back-end. Or can DBI somehow emulate the behavior of these databases? So there really isn't any way out - the back-ends are just too different. With good use of classes you can at least separate the databases from the functional code in your particular application. Cheers, Fabian -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 240 bytes Desc: This is a digitally signed message part Url : http://mailman.modpython.org/pipermail/mod_python/attachments/20020909/f0263eda/attachment-0003.bin
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