diff --git a/tests/system-test/2-query/TD-12926.py b/tests/system-test/2-query/TD-12926.py
new file mode 100644
index 0000000000000000000000000000000000000000..575a65d9cef01967c75f7094f06b822975ce4cdb
--- /dev/null
+++ b/tests/system-test/2-query/TD-12926.py
@@ -0,0 +1,81 @@
+###################################################################
+#           Copyright (c) 2020 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 -*-
+
+from posixpath import split
+import sys
+import os 
+
+from util.log import *
+from util.cases import *
+from util.sql import *
+from util.dnodes import *
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+        
+        self.ts = 1420041600000 # 2015-01-01 00:00:00  this is begin time for first record
+        self.num = 10
+
+    def getBuildPath(self):
+        selfPath = os.path.dirname(os.path.realpath(__file__))
+
+        if ("community" in selfPath):
+            projPath = selfPath[:selfPath.find("community")]
+        else:
+            projPath = selfPath[:selfPath.find("tests")]
+
+        for root, dirs, files in os.walk(projPath):
+            if ("taosd" in files):
+                rootRealPath = os.path.dirname(os.path.realpath(root))
+                if ("packaging" not in rootRealPath):
+                    buildPath = root[:len(root) - len("/build/bin")]
+                    break
+        return buildPath
+
+
+    def caseDescription(self):
+
+        '''
+        case1 <wenzhouwww>: [TD-11389] : 
+            this test case is an test case for cache error , it will let  the cached data obtained by the client that has connected to taosd incorrect，
+            root cause : table schema is changed, tag hostname size is increased through schema-less insertion. The schema cache of client taos is not refreshed.
+
+        ''' 
+        return 
+
+   
+    def run(self):
+        tdSql.prepare()
+        tdSql.execute("use db")
+
+        functions_list = ["count","avg","twa","irate","sum","stddev","LEASTSQUARES","min","max","first","last","last_row()","top","bottom",
+        "spread","ceil","floor","round"]
+        os.system("taosBenchmark -t 10 -n 5 -y ")
+
+        params_list = ["(,)","(,,)","(current)","(current,,,)*tbname","(*),","(abc,,)"]
+        for func in functions_list:
+            for params in params_list:
+                sql = "select %s%s from test.meters;"%(func,params)
+                tdSql.error(sql)
+
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
+
+