fix regression, fixes #168

dataset/persistence/table.py

@@ -4,7 +4,7 @@ from hashlib import sha1
 from sqlalchemy.sql import and_, expression
 from sqlalchemy.sql.expression import ClauseElement
 from sqlalchemy.schema import Column, Index
-from sqlalchemy import alias, func
+from sqlalchemy import alias, false
 from dataset.persistence.util import guess_type, normalize_column_name
 from dataset.persistence.util import ResultIter
 from dataset.util import DatasetException
@@ -241,7 +241,7 @@ class Table(object):
         clauses = list(clauses)
         for k, v in args.items():
             if not self._has_column(k):
-                clauses.append(func.sum(1) == 2)
+                clauses.append(false())
             elif isinstance(v, (list, tuple)):
                 clauses.append(self.table.c[k].in_(v))
             else:

setup.py

@@ -8,7 +8,7 @@ if sys.version_info[:2] <= (2, 6):
 
 setup(
     name='dataset',
-    version='0.6.3',
+    version='0.6.4',
     description="Toolkit for Python-based data processing.",
     long_description="",
     classifiers=[