diff --git a/smartsql_util.py b/smartsql_util.py
new file mode 100644
index 0000000..3d9af65
--- /dev/null
+++ b/smartsql_util.py
@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Author: jack <jacktan.whu@foxmail.com>
+#
+
+from smartsql import Condition, Field
+
+
+def common_datetime_wheres(f_datetime, start_time=None, end_time=None):
+
+    if not isinstance(f_datetime, Field):
+        raise TypeError("f_datetime must be a Field instance")
+
+    wheres = Condition('TRUE')
+
+    if start_time is not None:
+        wheres &= (f_datetime >= start_time)
+
+    if end_time is not None:
+        wheres &= (f_datetime < end_time)
+
+    return wheres