diff --git a/omniduct/caches/base.py b/omniduct/caches/base.py
index d3b5278..8c96e6b 100644
--- a/omniduct/caches/base.py
+++ b/omniduct/caches/base.py
@@ -48,6 +48,10 @@ def wrapped(method, self, *args, **kwargs):
 
         if _renew or not _cache.has_key(_key, namespace=_namespace):  # noqa: has_key is not of a dictionary here
             value = method(self, **kwargs)
+            if value is None:
+                logger.warning("Method value returned None. Not saving to cache.")
+                return
+
             try:
                 _cache.set(
                     _key,
diff --git a/omniduct/databases/base.py b/omniduct/databases/base.py
index f247656..773b665 100644
--- a/omniduct/databases/base.py
+++ b/omniduct/databases/base.py
@@ -613,7 +613,7 @@ def _dataframe_to_table(self, df, table, if_exists='fail', **kwargs):
         raise NotImplementedError
 
     def _cursor_empty(self, cursor):
-        return False
+        return cursor is None
 
     def _parse_namespaces(self, name, level=0, defaults=None):
         return ParsedNamespaces.from_name(
diff --git a/omniduct/databases/sqlalchemy.py b/omniduct/databases/sqlalchemy.py
index 16d5bc2..a2006cc 100644
--- a/omniduct/databases/sqlalchemy.py
+++ b/omniduct/databases/sqlalchemy.py
@@ -86,9 +86,6 @@ def _dataframe_to_table(self, df, table, if_exists='fail', **kwargs):
         return df.to_sql(name=table.table, schema=table.database, con=self.engine,
                          index=False, if_exists=if_exists, **kwargs)
 
-    def _cursor_empty(self, cursor):
-        return False
-
     def _table_list(self, **kwargs):
         return self.query("SHOW TABLES", **kwargs)