diff --git a/tests/pytest/fulltest.sh b/tests/pytest/fulltest.sh
index 5ee33c421ea1a2da6949d057f6670353a09abd3d..9d1aef0dc5cc2cf266931ff6e8ba88794649686c 100755
--- a/tests/pytest/fulltest.sh
+++ b/tests/pytest/fulltest.sh
@@ -143,6 +143,7 @@ python3 ./test.py -f query/filterOtherTypes.py
 python3 ./test.py -f query/querySort.py
 python3 ./test.py -f query/queryJoin.py
 python3 ./test.py -f query/select_last_crash.py
+python3 ./test.py -f query/queryNullValueTest.py
 
 #stream
 python3 ./test.py -f stream/metric_1.py
diff --git a/tests/pytest/query/queryInsertValue.py b/tests/pytest/query/queryInsertValue.py
new file mode 100644
index 0000000000000000000000000000000000000000..856801b4ee162a35e1e4e4b864860180960a1432
--- /dev/null
+++ b/tests/pytest/query/queryInsertValue.py
@@ -0,0 +1,65 @@
+###################################################################
+#           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 sys
+import taos
+from util.log import *
+from util.cases import *
+from util.sql import *
+import numpy as np
+from util.dnodes import *
+
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+        
+        self.numOfRecords = 10
+        self.ts = 1537146000000    
+    
+    def restartTaosd(self):
+        tdDnodes.stop(1)
+        tdDnodes.start(1)
+        tdSql.execute("use db")
+
+    def run(self):
+        tdSql.prepare()
+
+        print("==============step1")
+
+        tdSql.execute(
+            "create table st (ts timestamp, speed int) tags(areaid int, loc nchar(20))")
+        tdSql.execute("create table t1 using st tags(1, 'beijing')")
+        tdSql.execute("insert into t1 values(now, 1)")
+        tdSql.query("select * from st")
+        tdSql.checkRows(1)
+
+        tdSql.execute("alter table st add column length int")
+        tdSql.execute("insert into t1 values(now, 1, 2)")
+        tdSql.query("select last(*) from st")
+        tdSql.checkData(0, 2, 2);
+
+        self.restartTaosd();
+
+        tdSql.query("select last(*) from st")
+        tdSql.checkData(0, 2, 2);
+
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
diff --git a/tests/pytest/query/queryNullValueTest.py b/tests/pytest/query/queryNullValueTest.py
new file mode 100644
index 0000000000000000000000000000000000000000..2ad1979e0bfb33246d087e85132341fdc6e0bdcd
--- /dev/null
+++ b/tests/pytest/query/queryNullValueTest.py
@@ -0,0 +1,181 @@
+###################################################################
+#           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 sys
+import taos
+from util.log import *
+from util.cases import *
+from util.sql import *
+import numpy as np
+from util.dnodes import *
+
+
+class TDTestCase:
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+        
+        self.numOfRecords = 10
+        self.ts = 1537146000000
+
+    def checkNullValue(self, result):
+        mx = np.array(result)
+        [rows, cols] = mx.shape
+        for i in range(rows):
+            for j in range(cols):
+                if j + 1 < cols and mx[i, j + 1] is not None:
+                    print(mx[i, j + 1])
+                    return False
+        return True
+    
+    def restartTaosd(self):
+        tdDnodes.stop(1)
+        tdDnodes.start(1)
+        tdSql.execute("use db")
+
+    def run(self):
+        tdSql.prepare()
+
+        print("==============step1")
+
+        tdSql.execute(
+            "create table meters (ts timestamp, col1 int) tags(tgcol1 int)")
+        tdSql.execute("create table t0 using meters tags(NULL)")
+
+        for i in range (self.numOfRecords):
+            tdSql.execute("insert into t0 values (%d, %d)" % (self.ts + i, i));
+
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col2 tinyint")
+        tdSql.execute("alter table meters drop column col1")        
+        tdSql.query("select * from meters")        
+        tdSql.checkRows(10)
+        tdSql.query("select col2 from meters")        
+        tdSql.checkRows(10)        
+
+        tdSql.execute("alter table meters add column col1 int")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col1 from meters")        
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col3 smallint")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col3 from meters")        
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col4 bigint")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col4 from meters")        
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col5 float")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col5 from meters")        
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col6 double")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col6 from meters")        
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col7 bool")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col7 from meters")        
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col8 binary(20)")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col8 from meters")        
+        tdSql.checkRows(10)
+
+        tdSql.execute("alter table meters add column col9 nchar(20)")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select col9 from meters")        
+        tdSql.checkRows(10)
+        
+        tdSql.execute("alter table meters add tag tgcol2 tinyint")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol2 from meters")
+        tdSql.checkRows(1)
+                
+
+        tdSql.execute("alter table meters add tag tgcol3 smallint")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol3 from meters")
+        tdSql.checkRows(1)
+        
+
+        tdSql.execute("alter table meters add tag tgcol4 bigint")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol4 from meters")
+        tdSql.checkRows(1)
+
+        tdSql.execute("alter table meters add tag tgcol5 float")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol5 from meters")
+        tdSql.checkRows(1)
+
+        tdSql.execute("alter table meters add tag tgcol6 double")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol6 from meters")
+        tdSql.checkRows(1)
+
+        tdSql.execute("alter table meters add tag tgcol7 bool")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol7 from meters")
+        tdSql.checkRows(1)
+
+        tdSql.execute("alter table meters add tag tgcol8 binary(20)")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol8 from meters")
+        tdSql.checkRows(1)
+
+        tdSql.execute("alter table meters add tag tgcol9 nchar(20)")
+        tdSql.query("select * from meters")
+        tdSql.checkRows(10)
+        tdSql.query("select tgcol9 from meters")
+        tdSql.checkRows(1)
+
+        self.restartTaosd()
+        tdSql.query("select * from meters")        
+        tdSql.checkRows(10)
+        if self.checkNullValue(tdSql.queryResult) is False:
+            tdLog.exit("non None value is detected")
+
+
+        
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
diff --git a/tests/pytest/regressiontest.sh b/tests/pytest/regressiontest.sh
index ccc6635ced9dd532bb62149a00608ba5a849d04f..24cd93f0fc58772e2d1741d9ee0119d9d5247357 100755
--- a/tests/pytest/regressiontest.sh
+++ b/tests/pytest/regressiontest.sh
@@ -140,6 +140,7 @@ python3 ./test.py -f query/queryJoin.py
 python3 ./test.py -f query/filterCombo.py
 python3 ./test.py -f query/queryNormal.py
 python3 ./test.py -f query/select_last_crash.py
+python3 ./test.py -f query/queryNullValueTest.py
 
 #stream
 python3 ./test.py -f stream/stream1.py