diff --git a/python/plugins/db_manager/db_plugins/postgis/connector.py b/python/plugins/db_manager/db_plugins/postgis/connector.py
index 100845718f5..fd712497a16 100644
--- a/python/plugins/db_manager/db_plugins/postgis/connector.py
+++ b/python/plugins/db_manager/db_plugins/postgis/connector.py
@@ -743,7 +743,7 @@ class PostGisDBConnector(DBConnector):
         self._commit()
 
     def commentTable(self, schema, tablename, comment=None, db):
-        if comment = None:
+        if comment == None:
             db.connector._execute(None, 'COMMENT ON TABLE "{0}"."{1}" IS NULL;'.format(schema, tablename))
         else:
             db.connector._execute(None, 'COMMENT ON TABLE "{0}"."{1}" IS E\'{2}\';'.format(schema, tablename, comment))
diff --git a/python/plugins/db_manager/db_plugins/spatialite/connector.py b/python/plugins/db_manager/db_plugins/spatialite/connector.py
index 84d4f92dbc5..05a95c70abd 100644
--- a/python/plugins/db_manager/db_plugins/spatialite/connector.py
+++ b/python/plugins/db_manager/db_plugins/spatialite/connector.py
@@ -582,7 +582,6 @@ class SpatiaLiteDBConnector(DBConnector):
     def addTableColumn(self, table, field_def):
         """ add a column to table """
         sql = u"ALTER TABLE %s ADD %s" % (self.quoteId(table), field_def)
-        self._execute_and_commit(sql)
         self._execute(None, sql)
 
         sql = u"SELECT InvalidateLayerStatistics(%s)" % (self.quoteId(table))