I have a list and want to pass thru django raw sql.
Here is my list
region = ['US','CA','UK']
I am pasting a part of raw sql here.
results = MMCode.objects.raw('select assigner, assignee from mm_code where date between %s and %s and country_code in %s',[fromdate,todate,region])
Now it gives the below error, when i execute it in django python shell
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 1412, in __iter__
query = iter(self.query)
File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 73, in __iter__
self._execute_query()
File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 87, in _execute_query
self.cursor.execute(self.sql, self.params)
File "/usr/local/lib/python2.6/dist-packages/django/db/backends/util.py", line 15, in execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python2.6/dist-packages/django/db/backends/mysql/base.py", line 86, in execute
return self.cursor.execute(query, args)
File "/usr/lib/pymo开发者_如何学编程dules/python2.6/MySQLdb/cursors.py", line 166, in execute
self.errorhandler(self, exc, value)
File "/usr/lib/pymodules/python2.6/MySQLdb/connections.py", line 35, in defaulterrorhandler
raise errorclass, errorvalue
DatabaseError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1")
I have tried by passing the tuple also but there is no use. Can some one help me.
Thanks Vikram
For PostgreSQL at least, a list/tuple parameter is converted into an array in SQL, e.g.
ARRAY['US', 'CA', 'UK']
When this is inserted into the given query, it results in invalid SQL -
SELECT assigner, assignee FROM mm_code
WHERE date BETWEEN '2014-02-01' AND '2014-02-05'
AND country_code IN ARRAY['US', 'CA', 'UK']
However, the 'in' clause in SQL is logically equivalent to -
SELECT assigner, assignee FROM mm_code
WHERE date BETWEEN %s AND %s
AND country_code = ANY(%s)
... and when this query is filled with the parameters, the resulting SQL is valid and works -
SELECT assigner, assignee FROM mm_code
WHERE date BETWEEN '2014-02-01' AND '2014-02-05'
AND country_code = ANY(ARRAY['US', 'CA', 'UK'])
I'm not sure if this works in the other databases though, and whether or not this changes how the query is planned.
Casting the list to a tuple does work in Postgres, although the same code fails under sqlite3 with DatabaseError: near "?": syntax error
so it seems this is backend-specific. Your line of code would become:
results = MMCode.objects.raw('select assigner, assignee from mm_code where date between %s and %s and country_code in %s',[fromdate,todate,tuple(region)])
I tested this on a clean Django 1.5.1 project with the following in bar/models.py:
from django.db import models
class MMCode(models.Model):
assigner = models.CharField(max_length=100)
assignee = models.CharField(max_length=100)
date = models.DateField()
country_code = models.CharField(max_length=2)
then at the shell:
>>> from datetime import date
>>> from bar.models import MMCode
>>>
>>> regions = ['US', 'CA', 'UK']
>>> fromdate = date.today()
>>> todate = date.today()
>>>
>>> results = MMCode.objects.raw('select id, assigner, assignee from bar_mmcode where date between %s and %s and country_code in %s',[fromdate,todate,tuple(regions)])
>>> list(results)
[]
(note that the query line is changed slightly here, to use the default table name created by Django, and to include the id
column in the output so that the ORM doesn't complain)
This is not a great solution, because you must make sure your "region" values are correctly escaped for SQL. However, this is the only thing I could get to work with Sqlite:
sql = ('select assigner, assignee from mm_code '
'where date between %%s and %%s and country_code in %s' % (tuple(region),))
results = MMCode.objects.raw(sql, [fromdate,todate])
I ran into exactly this problem today. Django has changed (we now have RawSQL()
and friends!), but the general solution is still the same.
According to https://stackoverflow.com/a/283801/532513 the general idea is to explicitly add the same numbers of placeholders to your SQL string as there are elements in your region
array.
Your code would then look like this:
sql = 'select assigner, assignee from mm_code where date between %s and %s and country_code in ({0})'\
.format(','.join([%s] * len(region)))
results = MMCode.objects.raw(sql, [fromdate,todate] + region)
Your sql string would then first become ... between %s and %s and country_code in (%s, %s, %s) ...
and your params would be effectively [fromdate, todate, 'US', 'CA', 'UK']
. This way, you allow the database backend to correctly escape and potentially encode each of the country codes.
Well i'm not against raw sql but you can use:
MMCode.objects.filter(country_code__in=region, date__range=[fromdate,todate])
hope this helps.
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