diff --git a/examples/c/tqdemo.c b/examples/c/tqdemo.c
new file mode 100644
index 0000000000000000000000000000000000000000..62bcde59fc565bd8d3877e5b5a444833fe66ee07
--- /dev/null
+++ b/examples/c/tqdemo.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// TAOS standard API example. The same syntax as MySQL, but only a subset
+// to compile: gcc -o tqdemo tqdemo.c -ltaos
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <taos.h>  // TAOS header file
+
+void print_results(TAOS *taos, char *qstr);
+
+int main(int argc, char *argv[]) {
+  char qstr[1024];
+  TAOS_RES *pSql = NULL;
+
+  // connect to server
+  if (argc < 2) {
+    printf("please input server-ip \n");
+    return 0;
+  }
+
+  TAOS *taos = taos_connect(argv[1], "root", "taosdata", NULL, 0);
+  if (taos == NULL) {
+    printf("failed to connect to server, reason:%s\n", "null taos" /*taos_errstr(taos)*/);
+    exit(1);
+  }
+  
+  TAOS_RES* res;
+  // create topic
+  res = taos_query(taos, "create topic tq_test partitions 10");
+  taos_free_result(res);
+
+  res = taos_query(taos, "use tq_test");
+  taos_free_result(res);
+
+  print_results(taos, "show stables");
+  print_results(taos, "show tables");
+
+  // insert data
+  for (int i = 0; i < 10; i++) {
+    char *sql = "insert into p%d values(now + %ds, %d, 'test')";
+    sprintf(qstr, sql, i, i, i);
+    res = taos_query(taos, qstr);
+    taos_free_result(res);
+  }
+
+  // query data
+  print_results(taos, "select * from tq_test.ps");
+
+  taos_close(taos);
+  taos_cleanup();
+}
+
+
+void print_results(TAOS *taos, char *qstr) {
+  TAOS_RES* res;
+  res = taos_query(taos, qstr);
+  if (res == NULL || taos_errno(res) != 0) {
+    printf("failed to select, reason:%s\n", taos_errstr(res));
+    taos_free_result(res);
+    exit(1);
+  }
+
+  TAOS_ROW    row;
+  int         rows = 0;
+  int         num_fields = taos_field_count(res);
+  TAOS_FIELD *fields = taos_fetch_fields(res);
+
+  printf("num_fields = %d\n", num_fields);
+  printf("%s result:\n", qstr);
+  // fetch the records row by row
+  while ((row = taos_fetch_row(res))) {
+    char temp[1024] = {0};
+    rows++;
+    taos_print_row(temp, row, fields, num_fields);
+    printf("%s\n", temp);
+  }
+  taos_free_result(res);
+}
diff --git a/tests/parallel_test/cases.task b/tests/parallel_test/cases.task
index 3f5a01e79dc15447f6a63f2a12dc597671951ec4..738662427c40d680299f15001bf960d38998117a 100644
--- a/tests/parallel_test/cases.task
+++ b/tests/parallel_test/cases.task
@@ -606,6 +606,7 @@
 7,,develop-test,python3 ./test.py -f 5-taos-tools/taosdump/taosdumpTestTypeBigInt.py 
 7,,develop-test,python3 ./test.py -f 2-query/function_timetruncate.py
 7,,develop-test,python3 ./test.py -f 2-query/function_timediff.py
+7,,pytest,python3 test.py -f tsdb/delete.py
 6,,system-test,python3 ./test.py -f 2-query/TD-12229.py 
 6,,system-test,python3 ./test.py -f 2-query/TD-11943.py 
 6,,system-test,python3 ./test.py -f 2-query/function_elapsed.py 
diff --git a/tests/pytest/dockerCluster/delete.py b/tests/pytest/dockerCluster/delete.py
new file mode 100644
index 0000000000000000000000000000000000000000..da4838368e8672d3dac443de9085221a6c9b5da2
--- /dev/null
+++ b/tests/pytest/dockerCluster/delete.py
@@ -0,0 +1,321 @@
+###################################################################
+#           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
+
+from numpy.lib.function_base import insert
+import taos
+from util.log import *
+from util.cases import *
+from util.sql import *
+import numpy as np
+
+# constant define
+WAITS = 10 # wait seconds
+
+class TDTestCase:
+    
+    updatecfgDict = {'numOfNodes': 3, '1':{'replica': 3}, '2':{'replica': 3}, '3':{'replica': 3}}
+    
+    # init
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor())
+        tdSql.prepare()
+        self.create_tables()
+        self.ts = 1500000000000
+
+
+    # run case  
+    def run(self):
+        # insert data
+        for i in range(10):
+            tbname = "t%d"%i
+            self.insert_data(tbname, self.ts, (i+1)*10000, 20000);
+
+        tdLog.debug(" INSERT data 10 tables ....... [OK]")  
+
+        # test base case
+        self.test_case1()
+        tdLog.debug(" DELETE test_case1 ............ [OK]")
+        # test advance case
+        self.test_case2()
+        tdLog.debug(" DELETE test_case2 ............ [OK]")
+        # test advance case
+        self.test_case3()
+        tdLog.debug(" DELETE test_case3 ............ [OK]")
+
+
+    # stop 
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+    #
+    # --------------- case  -------------------
+    #
+
+    # create table
+    def create_tables(self):
+        # super table
+        tdSql.execute("create table st(ts timestamp, i1 int) tags(area int)")
+        # child table
+        for i in range(10):
+          sql = "create table t%d using st tags(%d)"%(i, i)
+          tdSql.execute(sql)
+        
+        return 
+
+    # insert data1
+    def insert_data(self, tbname, ts_start, count, batch_num):
+        pre_insert = "insert into %s values"%tbname
+        sql = pre_insert
+        tdLog.debug("doing insert table %s rows=%d ..."%(tbname, count))
+        for i in range(count):
+            sql += " (%d,%d)"%(ts_start + i*1000, i)
+            if i >0 and i%batch_num == 0:
+                tdSql.execute(sql)
+                sql = pre_insert
+        # end sql        
+        if sql != pre_insert:
+            tdSql.execute(sql)
+
+        return
+
+    # test case1 base 
+    def test_case1(self):
+        # 
+        # delete from single table
+        #
+        
+        # where <
+        sql = "select count(*) from t0 where ts < 1500000120000"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 120)
+        
+        sql = "delete from t0 where ts < 1500000120000"
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(120)
+
+        sql = "select count(*) from t0"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 10000 - 120 )
+
+        sql = "select * from t0 limit 1"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 120)
+
+        # where > and <
+        sql = "delete from t0 where ts > 1500000240000 and ts <= 1500000300000"
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(60)
+        sql = "select count(*) from t0"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 10000 - 120 - 60)
+
+        sql = "select * from t0 limit 2 offset 120"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 240)
+        tdSql.checkData(1, 1, 301)
+
+        
+        # where >  delete 1000 rows from end
+        sql = "delete from t0 where ts >= 1500009000000; "
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(1000)
+        sql = "select count(*) from t0"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 10000 - 120 - 60 - 1000)
+        
+        sql = "select last_row(*) from t0; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 8999)
+
+        sql = "select last(*) from t0"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 8999)
+
+        # insert last_row
+        sql = "insert into t0 values(1500009999000,9999); "
+        tdSql.execute(sql)
+
+        sql = "select last_row(*) from t0; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 9999)
+
+        sql = "select last(*) from t0"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 9999)
+
+        # insert last 
+        sql = "insert into t0 values(1500010000000,10000); "
+        tdSql.execute(sql)
+        sql = "insert into t0 values(1500010002000,NULL); "
+        tdSql.execute(sql)
+        sql = "insert into t0 values(1500010001000,10001); "
+        tdSql.execute(sql)
+        sql = "delete from t0 where ts = 1500010001000;  "
+        tdSql.execute(sql)
+
+        sql = "select last_row(i1) from t0; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, None)
+
+        sql = "select last(i1) from t0; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 10000)
+
+        # delete whole
+        sql = "delete from t0;"
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(8823)
+        
+        return 
+
+    # test advance 
+    def test_case2(self):
+        # 
+        # delete from super table
+        #
+        
+        # where <
+        sql = "select count(*) from st where ts < 1500000120000;"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 9*120) #1080
+        
+        sql = "delete from st where ts < 1500000120000;"
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(9*120) #1080
+
+        sql = "select count(*) from st;"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 540000 - 9*120 )
+
+        sql = "select * from st limit 1;"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 120)
+
+        # where > and <
+        sql = "delete from st where ts > 1500000240000 and ts <= 1500000300000;"
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(9*60)
+        sql = "select count(*) from st;"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 540000 - 9*120 - 9*60)
+
+        sql = "select * from st limit 2 offset 120"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 240)
+        tdSql.checkData(1, 1, 301)
+
+        
+        # where >  delete 1000 rows from end
+        sql = "delete from st where ts >= 1500009000000; "
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(459000)
+        sql = "select count(*) from st;"
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 79380)
+        
+        sql = "select last_row(*) from st; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 8999)
+
+        sql = "select last(*) from st"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 8999)
+
+        # insert last_row
+        sql = "insert into t0 values(1500009999000,9999); "
+        tdSql.execute(sql)
+
+        sql = "select last_row(*) from st; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 9999)
+
+        sql = "select last(*) from st"
+        tdSql.query(sql)
+        tdSql.checkData(0, 1, 9999)
+
+        # insert last 
+        sql = "insert into t0 values(1500010000000,10000); "
+        tdSql.execute(sql)
+        sql = "insert into t0 values(1500010002000,NULL); "
+        tdSql.execute(sql)
+        sql = "insert into t0 values(1500010001000,10001); "
+        tdSql.execute(sql)
+        sql = "delete from t0 where ts = 1500010001000;  "
+        tdSql.execute(sql)
+
+        sql = "select last_row(i1) from st; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, None)
+
+        sql = "select last(i1) from st; "
+        tdSql.query(sql)
+        tdSql.checkData(0, 0, 10000)
+
+        # delete whole
+        sql = "delete from st;"
+        tdSql.execute(sql)
+        tdSql.checkAffectedRows(79383)
+        
+        return 
+    
+    # verify function results after delete
+    def test_case3(self):
+        tdSql.execute("create database test")
+        tdSql.execute("use test")
+        
+        self.create_tables()
+        # insert data
+        for i in range(10):
+            tbname = "t%d"%i
+            self.insert_data(tbname, self.ts, (i+1)*10000, 20000);
+                        
+        tdSql.query("select count(*) from st")
+        tdSql.checkData(0, 0, 550000)
+        count = tdSql.getData(0, 0)        
+        
+        tdSql.query("select sum(i1) from st")
+        sum = tdSql.getData(0, 0)
+        
+        tdSql.query("select avg(i1) from st")
+        avg = tdSql.getData(0, 0)
+        
+        tdSql.query("select count(*) from t0")
+        count1 = tdSql.getData(0, 0)
+        
+        tdSql.query("select sum(i1) from t0")
+        sum1 = tdSql.getData(0, 0)
+        
+        tdSql.query("select avg(i1) from t0")
+        avg1 = tdSql.getData(0, 0)
+        
+        tdSql.execute("delete from st where tbname='t0'")
+        tdSql.checkAffectedRows(count1)
+        
+        tdSql.query("select count(*) from st")        
+        tdSql.checkData(0, 0, count - count1)
+        
+        tdSql.query("select sum(i1) from st")
+        tdSql.checkData(0, 0, sum - sum1)
+        
+        tdSql.query("select avg(i1) from st")
+        tdSql.checkData(0, 0, (sum - sum1) / (count - count1))        
+
+#
+# add case with filename
+#
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
\ No newline at end of file
diff --git a/tests/pytest/functions/function_bottom.py b/tests/pytest/functions/function_bottom.py
index e9e5003f6f96a9d04bb70b3a867c3cba239d8bff..23dd48f9aa2d9b9475ae1ca5b588dd196d663e2a 100644
--- a/tests/pytest/functions/function_bottom.py
+++ b/tests/pytest/functions/function_bottom.py
@@ -135,6 +135,33 @@ class TDTestCase:
         tdSql.execute(sql)
         tdSql.query('select bottom(c,1) from meters interval(10a)')
         tdSql.checkData(0,1,0)
+        
+        # TD-15187 test case
+        tdSql.execute("create database dd keep 36500")
+        tdSql.execute("use dd")
+        tdSql.execute("create table table_1(ts timestamp , q_int int,q_bool bool)")
+        tdSql.execute("insert into table_1 (ts , q_int,q_bool) values(1630000000000, 1,0)")
+        tdSql.execute("insert into table_1 (ts , q_int,q_bool) values(1630000010000, 2,0)")
+        tdSql.execute("insert into table_1 (ts , q_int,q_bool) values(1630000020000, 3,0)")
+        tdSql.execute("insert into table_1 (ts , q_int,q_bool) values(1630000100000, 3,0)")
+        tdSql.execute("insert into table_1 (ts , q_int,q_bool) values(1630000110000, 2,0)")
+        tdSql.execute("insert into table_1 (ts , q_int,q_bool) values(1630000120000, 1,0)")
+        
+        tdSql.query("select BOTTOM(q_int,40) from table_1 SESSION(ts,10m) order by ts")
+        tdSql.checkData(0, 1, 1)
+        tdSql.checkData(1, 1, 2)
+        tdSql.checkData(2, 1, 3)
+        tdSql.checkData(3, 1, 3)
+        tdSql.checkData(4, 1, 2)
+        tdSql.checkData(5, 1, 1)
+        
+        tdSql.query("select BOTTOM(q_int,40) from table_1 SESSION(ts,10m) order by ts desc;")
+        tdSql.checkData(0, 1, 1)
+        tdSql.checkData(1, 1, 2)
+        tdSql.checkData(2, 1, 3)
+        tdSql.checkData(3, 1, 3)
+        tdSql.checkData(4, 1, 2)
+        tdSql.checkData(5, 1, 1)
 
     def stop(self):
         tdSql.close()
diff --git a/tests/pytest/tsdb/delete.py b/tests/pytest/tsdb/delete.py
index 7cfd910c46e1591b21c50b55af31a0113c4cd7bb..4d37504f14d98e00eb5112ffda70d675498a672a 100644
--- a/tests/pytest/tsdb/delete.py
+++ b/tests/pytest/tsdb/delete.py
@@ -60,6 +60,9 @@ class TDTestCase:
         # test advance case
         self.test_case2()
         tdLog.debug(" DELETE test_case2 ............ [OK]")
+        # test delete with functions
+        self.test_case3()
+        tdLog.debug(" DELETE test_case3 ............ [OK]")
 
 
     # stop 
@@ -277,6 +280,48 @@ class TDTestCase:
         tdSql.checkAffectedRows(79383)
         
         return 
+    
+    # verify function results after delete
+    def test_case3(self):
+        tdSql.execute("create database test")
+        tdSql.execute("use test")
+        
+        self.create_tables()
+        # insert data
+        for i in range(10):
+            tbname = "t%d"%i
+            self.insert_data(tbname, self.ts, (i+1)*10000, 20000);
+                        
+        tdSql.query("select count(*) from st")
+        tdSql.checkData(0, 0, 550000)
+        count = tdSql.getData(0, 0)        
+        
+        tdSql.query("select sum(i1) from st")
+        sum = tdSql.getData(0, 0)
+        
+        tdSql.query("select avg(i1) from st")
+        avg = tdSql.getData(0, 0)
+        
+        tdSql.query("select count(*) from t0")
+        count1 = tdSql.getData(0, 0)
+        
+        tdSql.query("select sum(i1) from t0")
+        sum1 = tdSql.getData(0, 0)
+        
+        tdSql.query("select avg(i1) from t0")
+        avg1 = tdSql.getData(0, 0)
+        
+        tdSql.execute("delete from st where tbname='t0'")
+        tdSql.checkAffectedRows(count1)
+        
+        tdSql.query("select count(*) from st")        
+        tdSql.checkData(0, 0, count - count1)
+        
+        tdSql.query("select sum(i1) from st")
+        tdSql.checkData(0, 0, sum - sum1)
+        
+        tdSql.query("select avg(i1) from st")
+        tdSql.checkData(0, 0, (sum - sum1) / (count - count1))        
 
 #
 # add case with filename