diff --git a/tests/examples/c/demo.c b/tests/examples/c/demo.c
index 34c785a271c4217f89803539b3f1cb6aa3ca1111..377f4c162e7106ec8b95bd528980e015431d327c 100644
--- a/tests/examples/c/demo.c
+++ b/tests/examples/c/demo.c
@@ -16,142 +16,52 @@
 // TAOS standard API example. The same syntax as MySQL, but only a subet
 // to compile: gcc -o demo demo.c -ltaos
 
-#include <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <taos.h>  // TAOS header file
-#include <sys/time.h>
-#include <inttypes.h>
-
-static int32_t doQuery(TAOS* taos, const char* sql) {
-  struct timeval t1 = {0};
-  gettimeofday(&t1, NULL);
-  
-  TAOS_RES* res = taos_query(taos, sql);
-  if (taos_errno(res) != 0) {
-    printf("failed to execute query, reason:%s\n", taos_errstr(taos));
-    return -1;
-  }
-  
-  TAOS_ROW row = NULL;
-  char buf[512] = {0};
-  
-  int32_t numOfFields = taos_num_fields(res);
-  TAOS_FIELD* pFields = taos_fetch_fields(res);
-  
-  int32_t i = 0;
-  while((row = taos_fetch_row(res)) != NULL) {
-    taos_print_row(buf, row, pFields, numOfFields);
-    printf("%d:%s\n", ++i, buf);
-    memset(buf, 0, 512);
-  }
-  
-  taos_free_result(res);
-  
-  struct timeval t2 = {0};
-  gettimeofday(&t2, NULL);
-  
-  printf("elapsed time:%"PRId64 " ms\n", ((t2.tv_sec*1000000 + t2.tv_usec) - (t1.tv_sec*1000000 + t1.tv_usec))/1000);
-  return 0;
-}
-
-void* oneLoader(void* param) {
-  TAOS* conn = (TAOS*) param;
-  
-  for(int32_t i = 0; i < 20000; ++i) {
-//    doQuery(conn, "show databases");
-    doQuery(conn, "use test");
-//    doQuery(conn, "describe t12");
-//    doQuery(conn, "show tables");
-//    doQuery(conn, "create table if not exists abc (ts timestamp, k int)");
-//    doQuery(conn, "select * from t12");
-  }
-  
-  return 0;
-}
-
-
-static __attribute__((unused)) void multiThreadTest(int32_t numOfThreads, void* conn) {
-  pthread_attr_t thattr;
-  pthread_attr_init(&thattr);
-  pthread_attr_setdetachstate(&thattr, PTHREAD_CREATE_JOINABLE);
-  
-  pthread_t* threadId = (pthread_t*)malloc(sizeof(pthread_t)*(uint32_t)numOfThreads);
-  
-  for (int i = 0; i < numOfThreads; ++i) {
-    pthread_create(&threadId[i], NULL, oneLoader, conn);
-  }
-  
-  for (int32_t i = 0; i < numOfThreads; ++i) {
-    pthread_join(threadId[i], NULL);
-  }
-  
-  free(threadId);
-  pthread_attr_destroy(&thattr);
-}
 
 int main(int argc, char *argv[]) {
   TAOS *    taos;
   char      qstr[1024];
   TAOS_RES *result;
-  
+
   // connect to server
   if (argc < 2) {
     printf("please input server-ip \n");
     return 0;
   }
-  
-  taos_options(TSDB_OPTION_CONFIGDIR, "~/sec/cfg");
-  
+
   // init TAOS
   taos_init();
-  
+
   taos = taos_connect(argv[1], "root", "taosdata", NULL, 0);
   if (taos == NULL) {
-    printf("failed to connect to server, reason:%s\n", taos_errstr(NULL));
+    printf("failed to connect to server, reason:%s\n", taos_errstr(taos));
     exit(1);
   }
-  
   printf("success to connect to server\n");
-//  doQuery(taos, "select c1,count(*) from group_db0.group_mt0 where c1<8 group by c1");
-//  doQuery(taos, "select * from test.m1");
-
-//  multiThreadTest(1, taos);
-//  doQuery(taos, "select tbname from test.m1");
-//   doQuery(taos, "select max(c1), min(c2), sum(c3), avg(c4), first(c7), last(c8), first(c9) from lm2_db0.lm2_stb0 where ts >= 1537146000000 and ts <= 1543145400000 and tbname in ('lm2_tb0') interval(1s) group by t1");
-//   doQuery(taos, "select max(c1), min(c2), sum(c3), avg(c4), first(c7), last(c8), first(c9) from lm2_db0.lm2_stb0 where ts >= 1537146000000 and ts <= 1543145400000 and tbname in ('lm2_tb0', 'lm2_tb1', 'lm2_tb2') interval(1s)");
-  for(int32_t i = 0; i < 200; ++i) {
-    doQuery(taos, "select * from lm2_db0.lm2_stb0");
-  }
-//  doQuery(taos, "create table t1(ts timestamp, k binary(12), f nchar(2))");
-  
-  taos_close(taos);
-  return 0;
-  
+
+
   taos_query(taos, "drop database demo");
   if (taos_query(taos, "create database demo") != 0) {
     printf("failed to create database, reason:%s\n", taos_errstr(taos));
     exit(1);
   }
   printf("success to create database\n");
-  
-  
+
   taos_query(taos, "use demo");
-  
-  
+
   // create table
   if (taos_query(taos, "create table m1 (ts timestamp, speed int)") != 0) {
     printf("failed to create table, reason:%s\n", taos_errstr(taos));
     exit(1);
   }
   printf("success to create table\n");
-  
-  
+
   // sleep for one second to make sure table is created on data node
   // taosMsleep(1000);
-  
-  
+
   // insert 10 records
   int i = 0;
   for (i = 0; i < 10; ++i) {
@@ -162,29 +72,21 @@ int main(int argc, char *argv[]) {
     //sleep(1);
   }
   printf("success to insert rows, total %d rows\n", i);
-  
-  
+
   // query the records
   sprintf(qstr, "SELECT * FROM m1");
-  if (taos_query(taos, qstr) != 0) {
-    printf("failed to select, reason:%s\n", taos_errstr(taos));
-    exit(1);
-  }
-  
-  if (result == NULL) {
-    printf("failed to get result, reason:%s\n", taos_errstr(taos));
+  result = taos_query(taos, qstr);
+  if (result == NULL || taos_errno(result) != 0) {
+    printf("failed to select, reason:%s\n", taos_errstr(result));
     exit(1);
   }
 
-//  TAOS_ROW    row;
-  
   TAOS_ROW    row;
   int         rows = 0;
   int         num_fields = taos_field_count(taos);
   TAOS_FIELD *fields = taos_fetch_fields(result);
   char        temp[256];
-  
-  
+
   printf("select * from table, result:\n");
   // fetch the records row by row
   while ((row = taos_fetch_row(result))) {
@@ -192,7 +94,7 @@ int main(int argc, char *argv[]) {
     taos_print_row(temp, row, fields, num_fields);
     printf("%s\n", temp);
   }
-  
+
   taos_free_result(result);
   printf("====demo end====\n\n");
   return getchar();