On Sun, 2007-07-01 at 05:46 +0000, Davide.D wrote:
> Like this? ( database: mysql )-->
> ...
> q = request.REQUEST['q']
> ...
> from django.db import connection
> cursor = connection.cursor()
> cursor.execute("SELECT * FROM table_1, table_2, table_3 WHERE
> part_number = %s", [q])
> resultset = cursor.fetchone()
>
> But it doesn't work:
>
> Exception Type: OperationalError
> Exception Value: (1052, "Column 'part_number' in where clause is
> ambiguous")
Yes. You have to create legal SQL. So the where constraint will need to
be something like "table_1.part_number = %s OR table_2.part_number = %
s', etc.
Or you could use a UNION statement and an articifical column to tell you
which part of the union is appearing in the result. For example,
"(SELECT 1, part_number from table1 where ...) UNION (SELECT 2,
part_number from table2 where ...)"
>
> and also the resultset is not a queryset, it's a tuple list?
>
> [ ( ... ), ( ... ), ( ... ) ]
That's correct. You are talking directly to the database and getting
back a set of results. You will then know that the first n1 columns in
the result are for model1, the next n2 are for model2, etc (what the
values of n1 and n2 are will depend on the number of fields in each
model). So you can write a function to to find which set of columns
aren't empty and create the appropriate model.
You are dealing directly with the database here, so normal database
interaction rules apply.
If you don't want to do that, just construct one queryset for each model
and then join the results together in Python. You get to decide which
trade-off you prefer: more queries and simpler code (appropriate if you
have only a few models and/or not many results) or fewer queries and
more complex Python code.
Regards,
Malcolm
--
What if there were no hypothetical questions?
http://www.pointy-stick.com/blog/
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