diff --git a/tests/pytest/util/common.py b/tests/pytest/util/common.py
new file mode 100644
index 0000000000000000000000000000000000000000..35abc4802f9de2080a6b6a166daf833c9cf04578
--- /dev/null
+++ b/tests/pytest/util/common.py
@@ -0,0 +1,53 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import random
+import string
+from util.sql import tdSql
+
+class TDCom:
+    def init(self, conn, logSql):
+        tdSql.init(conn.cursor(), logSql)
+
+    def cleanTb(self):
+        query_sql = "show stables"
+        res_row_list = tdSql.query(query_sql, True)
+        stb_list = map(lambda x: x[0], res_row_list)
+        for stb in stb_list:
+            tdSql.execute(f'drop table if exists {stb}')
+
+        query_sql = "show tables"
+        res_row_list = tdSql.query(query_sql, True)
+        tb_list = map(lambda x: x[0], res_row_list)
+        for tb in tb_list:
+            tdSql.execute(f'drop table if exists {tb}')
+
+    def getLongName(self, len, mode = "mixed"):
+        """
+            generate long name
+            mode could be numbers/letters/letters_mixed/mixed
+        """    
+        if mode == "numbers": 
+            chars = ''.join(random.choice(string.digits) for i in range(len))
+        elif mode == "letters": 
+            chars = ''.join(random.choice(string.ascii_letters.lower()) for i in range(len))
+        elif mode == "letters_mixed": 
+            chars = ''.join(random.choice(string.ascii_letters.upper() + string.ascii_letters.lower()) for i in range(len))
+        else:
+            chars = ''.join(random.choice(string.ascii_letters.lower() + string.digits) for i in range(len))
+        return chars
+
+    def close(self):
+        self.cursor.close()
+
+tdCom = TDCom()