id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
14091	Fix incorrect quoting in connection.queries	Daniel Roseman	Jacob	"The default implementation of `DatabaseOperations.last_executed_query` returns incorrectly quoted values for many common queries in MySQL. This means that  {{{connection.queries}}} does not properly reflect the query that was actually executed by the database, leading to hard-to-debug errors.

For example, given this model:
{{{
    class Foo(models.Model):
        name = models.CharField(max_length=10)
        added = models.DateTimeField()
}}}

doing this query:
{{{
    Foo.objects.filter(added__lte=datetime.datetime.today())
}}}

gives this result from connection.queries:
{{{
[{'sql': ""SELECT `foo_foo`.`id`, `foo_foo`.`name`, `foo_foo`.`added` FROM `foo_foo` WHERE `foo_foo`.`added` <= 2010-08-11 02:58:21  LIMIT 21"",
  'time': '0.052'}]
}}}
which is invalid SQL because the timestamp is not quoted at all - although the query actually sent to the db is correctly quoted. More seriously, doing something like this:
{{{
values = ((u'1', '2010-08-09T15:55:28'),
          (u'2', '2010-08-10T15:55:28'),
          (u'3', '2010-08-11T15:55:28'))
Foo.objects.extra(where=['(name, added) in %s'], params=[values])
}}}
wrongly reports that the `values` tuple has been correctly quoted:
{{{
[{'sql': ""SELECT `foo_foo`.`id`, `foo_foo`.`name`, `foo_foo`.`added` FROM `foo_foo` WHERE (name, added) in ((u'0', '2010-08-08T15:55:28'), 
(u'1', '2010-08-09T15:55:28'), (u'2', '2010-08-10T15:55:28'), (u'3', '2010-08-11T15:55:28')) LIMIT 21"",  'time': '0.052'}]
}}}
when in fact the query sent to the database is
{{{
SELECT `foo_foo`.`id`, `foo_foo`.`name`, `foo_foo`.`added` FROM `foo_foo` WHERE (name, added) in ((""\'0\'"", ""\'2010-08-09T15:55:28\'""), 
(""\'0\'"", ""\'2010-08-09T15:55:28\'""), (""\'0\'"", ""\'2010-08-09T15:55:28\'""), (""\'0\'"", ""\'2010-08-09T15:55:28\'""), (""\'0\'"", ""\'2010-08-09T15:55:28\'""), 
(""\'0\'"", ""\'2010-08-09T15:55:28\'""), (""\'0\'"", ""\'2010-08-09T15:55:28\'""), (""\'0\'"", ""\'2010-08-09T15:55:28\'""), (""\'0\'"", ""\'2010-08-09T15:55:28\'"")) 
}}}
which is obviously not what was intended.

The Postgres backend overrides the `last_executed_query` method to use the `cursor.query` atribute, ensuring that the query is correctly represented. MySQLdb actually provides a similar attribute, `cursor._executed`, and this should be used by the MySQL backend. Attached patch uses this, but falls back to the default implementation if the attribute is not populated (the current version of MySQLdb occasionally does not populate `_executed`, although this appears to be fixed in the forthcoming version 2.)

No tests attached, because I couldn't work out where to put them - happy to do so with some advice."	Bug	closed	Database layer (models, ORM)	1.2	Normal	fixed			Ready for checkin	1	0	0	0	0	0