diff --git a/src/client/src/tscPrepare.c b/src/client/src/tscPrepare.c
index 0068b23334c895d2ccb1b37aeda0712e8b29d9c9..1a76bd5e6193acd19e51507a53812215ace16df4 100644
--- a/src/client/src/tscPrepare.c
+++ b/src/client/src/tscPrepare.c
@@ -614,11 +614,8 @@ int taos_stmt_execute(TAOS_STMT* stmt) {
       tfree(pStmt->pSql->sqlstr);
       pStmt->pSql->sqlstr = sql;
       SSqlObj* pSql = taos_query((TAOS*)pStmt->taos, pStmt->pSql->sqlstr);
-      if (pSql != NULL) {
-        ret = pSql->res.code;
-      } else {
-        ret = terrno;
-      } 
+      ret = taos_errno(pSql);
+      taos_free_result(pSql);
     }
   }
   return ret;
diff --git a/tests/examples/c/prepare.c b/tests/examples/c/prepare.c
index cb45e8620d126ee280aeea586baeab01cd0dccc4..3b968aca07bcc71721a5a34772ecac8b039a6841 100644
--- a/tests/examples/c/prepare.c
+++ b/tests/examples/c/prepare.c
@@ -4,7 +4,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-
 #include "taos.h"
 
 
@@ -14,6 +13,7 @@ int main(int argc, char *argv[])
 {
   TAOS     *taos;
   TAOS_RES *result;
+  int      code;
   TAOS_STMT *stmt;
 
   // connect to server
@@ -29,23 +29,33 @@ int main(int argc, char *argv[])
   if (taos == NULL) {
     printf("failed to connect to db, reason:%s\n", taos_errstr(taos));
     exit(1);
-  }
+  }   
+
+  result = taos_query(taos, "drop database demo"); 
+  taos_free_result(result);
 
-  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));
+  result = taos_query(taos, "create database demo");
+  code = taos_errno(result);
+  if (code != 0) {
+    printf("failed to create database, reason:%s\n", taos_errstr(result));
+    taos_free_result(result);
     exit(1);
   }
+  taos_free_result(result);
 
-  taos_query(taos, "use demo");
-
+  result = taos_query(taos, "use demo");
+  taos_free_result(result);
 
   // create table
   const char* sql = "create table m1 (ts timestamp, b bool, v1 tinyint, v2 smallint, v4 int, v8 bigint, f4 float, f8 double, bin binary(40), blob nchar(10))";
-  if (taos_query(taos, sql) != 0) {
-    printf("failed to create table, reason:%s\n", taos_errstr(taos));
+  result = taos_query(taos, sql);
+  code = taos_errno(result);
+  if (code != 0) {
+    printf("failed to create table, reason:%s\n", taos_errstr(result));
+    taos_free_result(result);
     exit(1);
   }
+  taos_free_result(result);
 
   // sleep for one second to make sure table is created on data node
   // taosMsleep(1000);
@@ -130,7 +140,7 @@ int main(int argc, char *argv[])
   int is_null = 1;
 
   sql = "insert into m1 values(?,?,?,?,?,?,?,?,?,?)";
-  int code = taos_stmt_prepare(stmt, sql, 0);
+  code = taos_stmt_prepare(stmt, sql, 0);
   if (code != 0){
     printf("failed to execute taos_stmt_prepare. code:0x%x\n", code);
   }
@@ -159,7 +169,6 @@ int main(int argc, char *argv[])
     exit(1);
   }
   taos_stmt_close(stmt);
-  printf("==== success inset data ====.\n");
 
   // query the records
   stmt = taos_stmt_init(taos);