[Zope] ZSQL Methods and +

[Matt Miller]

I have just joined this list, so forgive me as I break my cardinal rule
of reaidng a list for a while before posting.

I am working on a banner ad rotation system for my Zope installation. 
To that end I am using a rather simple algorithm to determine which ad
should be shown:

Each time an ad is selected, ads not shown have their "notshown" count
incremented by 2.
An ad is selected whenever the number of impressions remaining PLUS its
"notshown" is the largest in the DB.

To that end I am trying to use the following query template to return
the pointers to the ad to be displayed:

select image, alt, id, imprem+notshown as fr
from ads where imprem > 0 order by fr DESC LIMIT 1

As I quickly discovered the use of the '+' causes Zope to choke with a
"keyError":

Error, exceptions.KeyError: unhandled 

SQL used:

select image, alt, id, imprem+notshown as fr
from ads where imprem > 0 order by fr desc LIMIT 1



Traceback (innermost last):
  File /usr/local/www/Zope-2.0.0b5/lib/python/ZPublisher/Publish.py,
line 209, in publish_module
  File /usr/local/www/Zope-2.0.0b5/lib/python/ZPublisher/Publish.py,
line 179, in publish
  File /usr/local/www/Zope-2.0.0b5/lib/python/Zope/__init__.py, line
199, in zpublisher_exception_hook
    (Object: getad)
  File /usr/local/www/Zope-2.0.0b5/lib/python/ZPublisher/Publish.py,
line 165, in publish
  File /usr/local/www/Zope-2.0.0b5/lib/python/ZPublisher/mapply.py, line
154, in mapply
    (Object: manage_test)
  File /usr/local/www/Zope-2.0.0b5/lib/python/ZPublisher/Publish.py,
line 102, in call_object
    (Object: manage_test)
  File /usr/local/www/Zope-2.0.0b5/lib/python/Shared/DC/ZRDB/DA.py, line
310, in manage_test
    (Object: getad)
  File /usr/local/www/Zope-2.0.0b5/lib/python/Shared/DC/ZRDB/DA.py, line
291, in manage_test
    (Object: getad)
  File /usr/local/www/Zope-2.0.0b5/lib/python/Shared/DC/ZRDB/DA.py, line
395, in __call__
    (Object: getad)
  File lib/python/Products/ZMySQLDA/db.py, line 191, in query
KeyError: (see above)

Is this a known problem?  Have I done something incredibly stupid?  I am
able to use this syntax from the mysql monitor as well as in perl
cripts.  I have tried various combos of parens and escaping, to no
avail.

Thanks.


-- 
Matt Miller
matt.miller@thelinuxstore.com