work around a bunch of bugs;

dataset/persistence/database.py

@@ -134,7 +134,7 @@ class Database(object):
         """
         Get a listing of all tables that exist in the database.
         """
-        return self._tables.keys()
+        return list(self._tables.keys())
 
     def __contains__(self, member):
         return member in self.tables

dataset/persistence/table.py

@@ -253,6 +253,8 @@ class Table(object):
 
             table.drop_column('created_at')
         """
+        if self.database.engine.dialect.name == 'sqlite':
+            raise NotImplementedError("SQLite does not support dropping columns.")
         self._check_dropped()
         self.database._acquire()
         try:

test/test_persistence.py

@@ -315,8 +315,11 @@ class TableTestCase(unittest.TestCase):
         assert 'date' in cols and 'temperature' in cols and 'place' in cols
 
     def test_drop_column(self):
-        self.tbl.drop_column('date')
-        assert 'date' not in self.tbl.columns
+        try:
+            self.tbl.drop_column('date')
+            assert 'date' not in self.tbl.columns
+        except NotImplementedError:
+            pass
 
     def test_iter(self):
         c = 0