diff --git a/docs/examples/c/connect_example.c b/docs/examples/c/connect_example.c
index f31db557cc..53d2d0d59b 100644
--- a/docs/examples/c/connect_example.c
+++ b/docs/examples/c/connect_example.c
@@ -8,19 +8,15 @@ int main() {
   const char *host = "localhost";
   const char *user = "root";
   const char *passwd = "taosdata";
-  // if don't want to connect to a default db, set it to NULL or ""
-  const char *db = NULL;
-  uint16_t    port = 0;  // 0 means use the default port
+  const char *db = NULL;      // if don't want to connect to a default db, set it to NULL or ""
+  uint16_t    port = 6030;    // 0 means use the default port
   TAOS       *taos = taos_connect(host, user, passwd, db, port);
   if (taos == NULL) {
-    int errno = taos_errno(NULL);
-    const char *msg = taos_errstr(NULL);
-    printf("%d, %s\n", errno, msg);
-    printf("failed to connect to server %s, errno: %d, msg: %s\n", host, errno, msg);
+    printf("Failed to connect to %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
     taos_cleanup();
     return -1;
   }
-  printf("success to connect server %s\n", host);
+  printf("Connected to %s:%hu successfully.\n", host, port);
   
   /* put your code here for read and write */
 
diff --git a/docs/examples/c/create_db_demo.c b/docs/examples/c/create_db_demo.c
index 32168edcaa..ff1f4e62fd 100644
--- a/docs/examples/c/create_db_demo.c
+++ b/docs/examples/c/create_db_demo.c
@@ -25,47 +25,44 @@
 
 static int DemoCreateDB() {
 // ANCHOR: create_db_and_table
-const char *ip        = "localhost";
+const char *host      = "localhost";
 const char *user      = "root";
 const char *password  = "taosdata";
+uint16_t    port      = 6030;
+int code  = 0;
 
 // connect
-TAOS *taos = taos_connect(ip, user, password, NULL, 0);
+TAOS *taos = taos_connect(host, user, password, NULL, port);
 if (taos == NULL) {
-  printf("failed to connect to server %s, reason: %s\n", ip, taos_errstr(NULL));
+  printf("Failed to connect to %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
   taos_cleanup();
   return -1;
 }
-printf("success to connect server %s\n", ip);
 
 // create database
 TAOS_RES *result = taos_query(taos, "CREATE DATABASE IF NOT EXISTS power");
-int code = taos_errno(result);
+code = taos_errno(result);
 if (code != 0) {
-  printf("failed to create database power, reason: %s\n", taos_errstr(result));
+  printf("Failed to create database power, Server: %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
 }
 taos_free_result(result);
-printf("success to create database power\n");
-
-// use database
-result = taos_query(taos, "USE power");
-taos_free_result(result);
+printf("Create database power successfully.\n");
 
 // create table
-const char* sql = "CREATE STABLE IF NOT EXISTS meters (ts TIMESTAMP, current FLOAT, voltage INT, phase FLOAT) TAGS (groupId INT, location BINARY(24))";
+const char* sql = "CREATE STABLE IF NOT EXISTS power.meters (ts TIMESTAMP, current FLOAT, voltage INT, phase FLOAT) TAGS (groupId INT, location BINARY(24))";
 result = taos_query(taos, sql);
 code = taos_errno(result);
 if (code != 0) {
-  printf("failed to create stable meters, reason: %s\n", taos_errstr(result));
+  printf("Failed to create stable power.meters, Server: %s:%hu, ErrCode: 0x%x, ErrMessage: %s\n.", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
 }
 taos_free_result(result);
-printf("success to create table meters\n");
+printf("Create stable meters successfully.\n");
 
 // close & clean
 taos_close(taos);
diff --git a/docs/examples/c/insert_data_demo.c b/docs/examples/c/insert_data_demo.c
index 03e86d7f2c..8796556d03 100644
--- a/docs/examples/c/insert_data_demo.c
+++ b/docs/examples/c/insert_data_demo.c
@@ -24,22 +24,19 @@
 
 static int DemoInsertData() {
 // ANCHOR: insert_data
-const char *ip        = "localhost";
+const char *host      = "localhost";
 const char *user      = "root";
 const char *password  = "taosdata";
+uint16_t    port      = 6030;
+int code  = 0;
 
 // connect
-TAOS *taos = taos_connect(ip, user, password, NULL, 0);
+TAOS *taos = taos_connect(host, user, password, NULL, port);
 if (taos == NULL) {
-  printf("failed to connect to server %s, reason: %s\n", ip, taos_errstr(NULL));
+  printf("Failed to connect to %s:%hu; ErrCode: 0x%x; ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
   taos_cleanup();
   return -1;
 }
-printf("success to connect server %s\n", ip);
-
-// use database
-TAOS_RES *result = taos_query(taos, "USE power");
-taos_free_result(result);
 
 // insert data, please make sure the database and table are already created
 const char* sql = "INSERT INTO "                                                  \
@@ -51,10 +48,10 @@ const char* sql = "INSERT INTO "
           "power.d1002 USING power.meters TAGS(3, 'California.SanFrancisco') "    \
           "VALUES "                                                               \
           "(NOW + 1a, 10.30000, 218, 0.25000) ";
-result = taos_query(taos, sql);
-int code = taos_errno(result);
+TAOS_RES *result = taos_query(taos, sql);
+code = taos_errno(result);
 if (code != 0) {
-  printf("failed to insert data to power.meters, ip: %s, reason: %s\n", ip, taos_errstr(result));
+  printf("Failed to insert data to power.meters, Server: %s:%hu; ErrCode: 0x%x; ErrMessage: %s\n.", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
@@ -63,7 +60,7 @@ taos_free_result(result);
 
 // you can check affectedRows here
 int rows = taos_affected_rows(result);
-printf("success to insert %d rows data to power.meters\n", rows);
+printf("Successfully inserted %d rows into power.meters.\n", rows);
 
 // close & clean
 taos_close(taos);
diff --git a/docs/examples/c/query_data_demo.c b/docs/examples/c/query_data_demo.c
index 02f54b537c..77af4c9a8d 100644
--- a/docs/examples/c/query_data_demo.c
+++ b/docs/examples/c/query_data_demo.c
@@ -25,29 +25,28 @@
 
 static int DemoQueryData() {
 // ANCHOR: query_data
-const char *ip        = "localhost";
+const char *host      = "localhost";
 const char *user      = "root";
 const char *password  = "taosdata";
+uint16_t    port      = 6030;
+int code  = 0;
 
 // connect
-TAOS *taos = taos_connect(ip, user, password, NULL, 0);
+TAOS *taos = taos_connect(host, user, password, NULL, port);
 if (taos == NULL) {
-  printf("failed to connect to server %s, reason: %s\n", ip, taos_errstr(NULL));
+  printf("Failed to connect to %s:%hu; ErrCode: 0x%x; ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
   taos_cleanup();
   return -1;
 }
-printf("success to connect server %s\n", ip);
 
-// use database
-TAOS_RES *result = taos_query(taos, "USE power");
-taos_free_result(result);
+
 
 // query data, please make sure the database and table are already created
 const char* sql = "SELECT ts, current, location FROM power.meters limit 100";
-result = taos_query(taos, sql);
-int code = taos_errno(result);
+TAOS_RES *result = taos_query(taos, sql);
+code = taos_errno(result);
 if (code != 0) {
-  printf("failed to query data from power.meters, ip: %s, reason: %s\n", ip, taos_errstr(result));
+  printf("Failed to query data from power.meters, Server: %s:%hu; ErrCode: 0x%x; ErrMessage: %s\n.", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
@@ -70,7 +69,6 @@ while ((row = taos_fetch_row(result))) {
 }
 printf("total rows: %d\n", rows);
 taos_free_result(result);
-printf("success to query data from power.meters\n");
 
 // close & clean
 taos_close(taos);
diff --git a/docs/examples/c/sml_insert_demo.c b/docs/examples/c/sml_insert_demo.c
index 0c4be1d6f8..65636d89b8 100644
--- a/docs/examples/c/sml_insert_demo.c
+++ b/docs/examples/c/sml_insert_demo.c
@@ -24,33 +24,41 @@
 
 static int DemoSmlInsert() {
 // ANCHOR: schemaless
-const char *ip        = "localhost";
+const char *host      = "localhost";
 const char *user      = "root";
 const char *password  = "taosdata";
+uint16_t    port      = 6030;
+int code  = 0;
 
 // connect
-TAOS *taos = taos_connect(ip, user, password, NULL, 0);
+TAOS *taos = taos_connect(host, user, password, NULL, port);
 if (taos == NULL) {
-  printf("failed to connect to server %s, reason: %s\n", ip, taos_errstr(NULL));
+  printf("Failed to connect to %s:%hu; ErrCode: 0x%x; ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
   taos_cleanup();
   return -1;
 }
-printf("success to connect server %s\n", ip);
 
 // create database
 TAOS_RES *result = taos_query(taos, "CREATE DATABASE IF NOT EXISTS power");
-int code = taos_errno(result);
+code = taos_errno(result);
 if (code != 0) {
-  printf("failed to create database power, reason: %s\n", taos_errstr(result));
+  printf("Failed to create database power, Server: %s:%hu; ErrCode: 0x%x; ErrMessage: %s.\n", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
 }
 taos_free_result(result);
-printf("success to create database power\n");
+printf("Create database power successfully.\n");
 
 // use database
 result = taos_query(taos, "USE power");
+code = taos_errno(result);
+if (code != 0) {
+  printf("Failed to execute use power, Server: %s:%hu; ErrCode: 0x%x; ErrMessage: %s\n.", host, port, code, taos_errstr(result));
+  taos_close(taos);
+  taos_cleanup();
+  return -1;
+}
 taos_free_result(result);
 
 // schemaless demo data
@@ -61,29 +69,31 @@ char * json_demo = "{\"metric\": \"metric_json\",\"timestamp\": 1626846400,\"val
 // influxdb line protocol
 char *lines[] = {line_demo};
 result = taos_schemaless_insert(taos, lines, 1, TSDB_SML_LINE_PROTOCOL, TSDB_SML_TIMESTAMP_MILLI_SECONDS);
-if (taos_errno(result) != 0) {
-  printf("failed to insert schemaless line data, reason: %s\n", taos_errstr(result));
+code = taos_errno(result);
+if (code != 0) {
+  printf("Failed to insert schemaless line data, Server: %s:%hu; ErrCode: 0x%x; ErrMessage: %s\n.", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
 }
 
 int rows = taos_affected_rows(result);
-printf("success to insert %d rows of schemaless line data\n", rows);
+printf("Insert %d rows of schemaless line data successfully.\n", rows);
 taos_free_result(result);
 
 // opentsdb telnet protocol
 char *telnets[] = {telnet_demo};
 result = taos_schemaless_insert(taos, telnets, 1, TSDB_SML_TELNET_PROTOCOL, TSDB_SML_TIMESTAMP_MILLI_SECONDS);
-if (taos_errno(result) != 0) {
-  printf("failed to insert schemaless telnet data, reason: %s\n", taos_errstr(result));
+code = taos_errno(result);
+if (code != 0) {
+  printf("Failed to insert schemaless telnet data, Server: %s:%hu; ErrCode: 0x%x; ErrMessage: %s\n.", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
 }
 
 rows = taos_affected_rows(result);
-printf("success to insert %d rows of schemaless telnet data\n", rows);
+printf("Insert %d rows of schemaless telnet data successfully.\n", rows);
 taos_free_result(result);
 
 // opentsdb json protocol
@@ -91,16 +101,17 @@ char *jsons[1] = {0};
 // allocate memory for json data. can not use static memory.
 jsons[0] = malloc(1024);
 if (jsons[0] == NULL) {
-  printf("failed to allocate memory\n");
+  printf("Failed to allocate memory\n");
   taos_close(taos);
   taos_cleanup();
   return -1;
 }
 (void)strncpy(jsons[0], json_demo, 1023);
 result = taos_schemaless_insert(taos, jsons, 1, TSDB_SML_JSON_PROTOCOL, TSDB_SML_TIMESTAMP_NOT_CONFIGURED);
-if (taos_errno(result) != 0) {
+code = taos_errno(result);
+if (code != 0) {
   free(jsons[0]);
-  printf("failed to insert schemaless json data, reason: %s\n", taos_errstr(result));
+  printf("Failed to insert schemaless json data, Server: %s:%hu; ErrCode: 0x%x; ErrMessage: %s\n.", host, port, code, taos_errstr(result));
   taos_close(taos);
   taos_cleanup();
   return -1;
@@ -108,7 +119,7 @@ if (taos_errno(result) != 0) {
 free(jsons[0]);
 
 rows = taos_affected_rows(result);
-printf("success to insert %d rows of schemaless json data\n", rows);
+printf("Insert %d rows of schemaless json data successfully.\n", rows);
 taos_free_result(result);
 
 // close & clean
diff --git a/docs/examples/c/stmt_insert_demo.c b/docs/examples/c/stmt_insert_demo.c
index ba953a856f..854c9f86e2 100644
--- a/docs/examples/c/stmt_insert_demo.c
+++ b/docs/examples/c/stmt_insert_demo.c
@@ -64,6 +64,7 @@ typedef struct {
 
 int num_of_sub_table = 10;
 int num_of_row = 10;
+int total_affected = 0;
 /**
  * @brief insert data using stmt API
  *
@@ -72,10 +73,14 @@ int num_of_row = 10;
 void insertData(TAOS *taos) {
   // init
   TAOS_STMT *stmt = taos_stmt_init(taos);
+  if (stmt == NULL) {
+      printf("Failed to init taos_stmt, error: %s\n", taos_stmt_errstr(NULL));
+      exit(EXIT_FAILURE);
+  }
   // prepare
   const char *sql = "INSERT INTO ? USING meters TAGS(?,?) VALUES (?,?,?,?)";
   int         code = taos_stmt_prepare(stmt, sql, 0);
-  checkErrorCode(stmt, code, "failed to execute taos_stmt_prepare");
+  checkErrorCode(stmt, code, "Failed to execute taos_stmt_prepare");
   for (int i = 1; i <= num_of_sub_table; i++) {
     char table_name[20];
     sprintf(table_name, "d_bind_%d", i);
@@ -99,7 +104,7 @@ void insertData(TAOS *taos) {
     tags[1].is_null = NULL;
     tags[1].num = 1;
     code = taos_stmt_set_tbname_tags(stmt, table_name, tags);
-    checkErrorCode(stmt, code, "failed to set table name and tags\n");
+    checkErrorCode(stmt, code, "Failed to set table name and tags\n");
 
     // insert rows
     TAOS_MULTI_BIND params[4];
@@ -142,25 +147,31 @@ void insertData(TAOS *taos) {
       params[3].buffer = &phase;
       // bind param
       code = taos_stmt_bind_param(stmt, params);
-      checkErrorCode(stmt, code, "failed to bind param");
+      checkErrorCode(stmt, code, "Failed to bind param");
     }
     // add batch
     code = taos_stmt_add_batch(stmt);
-    checkErrorCode(stmt, code, "failed to add batch");
+    checkErrorCode(stmt, code, "Failed to add batch");
     // execute batch
     code = taos_stmt_execute(stmt);
-    checkErrorCode(stmt, code, "failed to exec stmt");
+    checkErrorCode(stmt, code, "Failed to exec stmt");
     // get affected rows
     int affected = taos_stmt_affected_rows_once(stmt);
-    printf("table %s insert %d rows.\n", table_name, affected);
+    total_affected += affected;
   }
+  printf("Successfully inserted %d rows to power.meters.\n", total_affected);
   taos_stmt_close(stmt);
 }
 
 int main() {
-  TAOS *taos = taos_connect("localhost", "root", "taosdata", NULL, 6030);
+  const char *host      = "localhost";
+  const char *user      = "root";
+  const char *password  = "taosdata";
+  uint16_t    port      = 6030;
+  TAOS *taos = taos_connect(host, user, password, NULL, port);
   if (taos == NULL) {
-    printf("failed to connect to server\n");
+    printf("Failed to connect to %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
+    taos_cleanup();
     exit(EXIT_FAILURE);
   }
   // create database and table
diff --git a/docs/examples/c/tmq_demo.c b/docs/examples/c/tmq_demo.c
index adce4bbd5f..d3285cb2d0 100644
--- a/docs/examples/c/tmq_demo.c
+++ b/docs/examples/c/tmq_demo.c
@@ -13,6 +13,8 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+// to compile: gcc -o tmq_demo tmq_demo.c -ltaos -lpthread
+
 #include <assert.h>
 #include <pthread.h>
 #include <stdio.h>
@@ -27,8 +29,15 @@ static int   running = 1;
 const char*  topic_name = "topic_meters";
 
 void* prepare_data(void* arg) {
-  TAOS* pConn = taos_connect("localhost", "root", "taosdata", NULL, 0);
+  const char *host      = "localhost";
+  const char *user      = "root";
+  const char *password  = "taosdata";
+  uint16_t    port      = 6030;
+  int code = 0;
+  TAOS *pConn = taos_connect(host, user, password, NULL, port);
   if (pConn == NULL) {
+    fprintf(stderr, "Failed to connect to %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
+    taos_cleanup();
     return NULL;
   }
 
@@ -45,13 +54,14 @@ void* prepare_data(void* arg) {
         i);
 
     pRes = taos_query(pConn, buf);
-    if (taos_errno(pRes) != 0) {
-      printf("error in insert data to power.meters, reason:%s\n", taos_errstr(pRes));
+    code = taos_errno(pRes);
+    if (code != 0) {
+      fprintf(stderr, "Failed to insert data to power.meters, ErrCode: 0x%x, ErrMessage: %s.\n", code, taos_errstr(pRes));
     }
     taos_free_result(pRes);
     sleep(1);
   }
-  printf("prepare data thread exit\n");
+  fprintf(stdout, "Prepare data thread exit\n");
   return NULL;
 }
 
@@ -63,9 +73,9 @@ static int32_t msg_process(TAOS_RES* msg) {
   const char* dbName = tmq_get_db_name(msg);
   int32_t     vgroupId = tmq_get_vgroup_id(msg);
 
-  printf("topic: %s\n", topicName);
-  printf("db: %s\n", dbName);
-  printf("vgroup id: %d\n", vgroupId);
+  fprintf(stdout, "topic: %s\n", topicName);
+  fprintf(stdout, "db: %s\n", dbName);
+  fprintf(stdout, "vgroup id: %d\n", vgroupId);
 
   while (1) {
     // get one row data from message
@@ -81,11 +91,11 @@ static int32_t msg_process(TAOS_RES* msg) {
     rows++;
     // print the row content
     if (taos_print_row(buf, row, fields, numOfFields) < 0) {
-      printf("failed to print row\n");
+      fprintf(stderr, "Failed to print row\n");
       break;
     }
     // print the precision and row content to the console
-    printf("precision: %d, row content: %s\n", precision, buf);
+    fprintf(stdout, "precision: %d, data: %s\n", precision, buf);
   }
 
   return rows;
@@ -93,42 +103,53 @@ static int32_t msg_process(TAOS_RES* msg) {
 // ANCHOR_END: msg_process
 
 static int32_t init_env() {
-  TAOS* pConn = taos_connect("localhost", "root", "taosdata", NULL, 0);
+  const char *host      = "localhost";
+  const char *user      = "root";
+  const char *password  = "taosdata";
+  uint16_t    port      = 6030;
+  int code = 0;
+  TAOS *pConn = taos_connect(host, user, password, NULL, port);
   if (pConn == NULL) {
+    fprintf(stderr, "Failed to connect to %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
+    taos_cleanup();
     return -1;
   }
 
   TAOS_RES* pRes;
   // drop database if exists
-  printf("create database\n");
-  pRes = taos_query(pConn, "drop topic if exists topic_meters");
-  if (taos_errno(pRes) != 0) {
-    printf("error in drop topic_meters, reason:%s\n", taos_errstr(pRes));
+  fprintf(stdout, "Create database.\n");
+  pRes = taos_query(pConn, "DROP TOPIC IF EXISTS topic_meters");
+  code = taos_errno(pRes);
+  if (code != 0) {
+    fprintf(stderr, "Failed to drop topic_meters, ErrCode: 0x%x, ErrMessage: %s.\n", code, taos_errstr(pRes));
   }
   taos_free_result(pRes);
 
-  pRes = taos_query(pConn, "drop database if exists power");
-  if (taos_errno(pRes) != 0) {
-    printf("error in drop power, reason:%s\n", taos_errstr(pRes));
+  pRes = taos_query(pConn, "DROP DATABASE IF EXISTS power");
+  code = taos_errno(pRes);
+  if (code != 0) {
+    fprintf(stderr, "Failed to drop database power, ErrCode: 0x%x, ErrMessage: %s.\n", code, taos_errstr(pRes));
   }
   taos_free_result(pRes);
 
   // create database
-  pRes = taos_query(pConn, "create database power precision 'ms' WAL_RETENTION_PERIOD 3600");
-  if (taos_errno(pRes) != 0) {
-    printf("error in create tmqdb, reason:%s\n", taos_errstr(pRes));
+  pRes = taos_query(pConn, "CREATE DATABASE power PRECISION 'ms' WAL_RETENTION_PERIOD 3600");
+  code = taos_errno(pRes);
+  if (code != 0) {
+    fprintf(stderr, "Failed to create tmqdb, ErrCode: 0x%x, ErrMessage: %s.\n", code, taos_errstr(pRes));
     goto END;
   }
   taos_free_result(pRes);
 
   // create super table
-  printf("create super table\n");
+  fprintf(stdout, "Create super table.\n");
   pRes = taos_query(
       pConn,
       "CREATE STABLE IF NOT EXISTS power.meters (ts TIMESTAMP, current FLOAT, voltage INT, phase FLOAT) TAGS "
       "(groupId INT, location BINARY(24))");
-  if (taos_errno(pRes) != 0) {
-    printf("failed to create super table meters, reason:%s\n", taos_errstr(pRes));
+  code = taos_errno(pRes);
+  if (code != 0) {
+    fprintf(stderr, "Failed to create super table meters, ErrCode: 0x%x, ErrMessage: %s.\n", code, taos_errstr(pRes));
     goto END;
   }
 
@@ -143,16 +164,24 @@ END:
 }
 
 int32_t create_topic() {
-  printf("create topic\n");
+  fprintf(stdout, "Create topic.\n");
   TAOS_RES* pRes;
-  TAOS*     pConn = taos_connect("localhost", "root", "taosdata", NULL, 0);
+  const char *host      = "localhost";
+  const char *user      = "root";
+  const char *password  = "taosdata";
+  uint16_t    port      = 6030;
+  int code = 0;
+  TAOS *pConn = taos_connect(host, user, password, NULL, port);
   if (pConn == NULL) {
+    fprintf(stderr, "Failed to connect to %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
+    taos_cleanup();
     return -1;
   }
 
-  pRes = taos_query(pConn, "use power");
+  pRes = taos_query(pConn, "USE POWER");
+  code = taos_errno(pRes);
   if (taos_errno(pRes) != 0) {
-    printf("error in use tmqdb, reason:%s\n", taos_errstr(pRes));
+    fprintf(stderr, "Failed to use tmqdb, ErrCode: 0x%x, ErrMessage: %s.\n", code, taos_errstr(pRes));
     return -1;
   }
   taos_free_result(pRes);
@@ -160,8 +189,9 @@ int32_t create_topic() {
   pRes = taos_query(
       pConn,
       "CREATE TOPIC IF NOT EXISTS topic_meters AS SELECT ts, current, voltage, phase, groupid, location FROM meters");
-  if (taos_errno(pRes) != 0) {
-    printf("failed to create topic topic_meters, reason:%s\n", taos_errstr(pRes));
+  code = taos_errno(pRes);
+  if (code != 0) {
+    fprintf(stderr, "Failed to create topic topic_meters, ErrCode: 0x%x, ErrMessage: %s.\n", code, taos_errstr(pRes));
     return -1;
   }
   taos_free_result(pRes);
@@ -171,7 +201,7 @@ int32_t create_topic() {
 }
 
 void tmq_commit_cb_print(tmq_t* tmq, int32_t code, void* param) {
-  printf("tmq_commit_cb_print() code: %d, tmq: %p, param: %p\n", code, tmq, param);
+  fprintf(stdout, "tmq_commit_cb_print() code: %d, tmq: %p, param: %p\n", code, tmq, param);
 }
 
 // ANCHOR: create_consumer_1
@@ -243,6 +273,7 @@ tmq_list_t* build_topic_list() {
   if (code) {
     // if failed, destroy the list and return NULL
     tmq_list_destroy(topicList);
+    fprintf(stderr, "Failed to create topic_list, ErrCode: 0x%x, ErrMessage: %s.\n", code, tmq_err2str(code));
     return NULL;
   }
   // if success, return the list
@@ -285,7 +316,7 @@ void consume_repeatly(tmq_t* tmq) {
   // get the topic assignment
   int32_t code = tmq_get_topic_assignment(tmq, topic_name, &pAssign, &numOfAssignment);
   if (code != 0 || pAssign == NULL || numOfAssignment == 0) {
-    fprintf(stderr, "failed to get assignment, reason:%s", tmq_err2str(code));
+    fprintf(stderr, "Failed to get assignment, ErrCode: 0x%x, ErrMessage: %s.\n", code, tmq_err2str(code));
     return;
   }
 
@@ -295,7 +326,9 @@ void consume_repeatly(tmq_t* tmq) {
 
     code = tmq_offset_seek(tmq, topic_name, p->vgId, p->begin);
     if (code != 0) {
-      fprintf(stderr, "failed to seek to %d, reason:%s", (int)p->begin, tmq_err2str(code));
+      fprintf(stderr, "Failed to seek assignment %d to beginning %ld, ErrCode: 0x%x, ErrMessage: %s.\n", i, p->begin, code, tmq_err2str(code));
+    } else {
+      fprintf(stdout, "Seek assignment %d to beginning %ld successfully.\n", i, p->begin);
     }
   }
 
@@ -324,10 +357,12 @@ void manual_commit(tmq_t* tmq) {
       int32_t code = tmq_commit_sync(tmq, tmqmsg);
 
       if (code) {
-        fprintf(stderr, "Failed to commit message: %s\n", tmq_err2str(code));
+        fprintf(stderr, "Failed to commit message, ErrCode: 0x%x, ErrMessage: %s.\n", code, tmq_err2str(code));
         // free the message
         taos_free_result(tmqmsg);
         break;
+      } else {
+        fprintf(stdout, "Commit offset manually successfully.\n");
       }
       // free the message
       taos_free_result(tmqmsg);
@@ -339,7 +374,7 @@ void manual_commit(tmq_t* tmq) {
   }
 
   // print the result: total messages and total rows consumed
-  fprintf(stderr, "%d msg consumed, include %d rows\n", msgCnt, totalRows);
+  fprintf(stderr, "%d msg consumed, include %d rows.\n", msgCnt, totalRows);
 }
 // ANCHOR_END: manual_commit
 
@@ -356,28 +391,31 @@ int main(int argc, char* argv[]) {
   }
 
   if (pthread_create(&thread_id, NULL, &prepare_data, NULL)) {
-    fprintf(stderr, "create thread failed\n");
+    fprintf(stderr, "Failed to create thread.\n");
     return 1;
   }
 
   // ANCHOR: create_consumer_2
   tmq_t* tmq = build_consumer();
   if (NULL == tmq) {
-    fprintf(stderr, "build consumer to localhost fail!\n");
+    fprintf(stderr, "Failed to create consumer.\n");
     return -1;
   }
-  printf("build consumer to localhost successfully \n");
+  fprintf(stdout, "Create consumer successfully.\n");
 
   // ANCHOR_END: create_consumer_2
 
   // ANCHOR: subscribe_3
   tmq_list_t* topic_list = build_topic_list();
   if (NULL == topic_list) {
+    fprintf(stderr, "Failed to create topic_list.\n");
     return -1;
   }
 
   if ((code = tmq_subscribe(tmq, topic_list))) {
-    fprintf(stderr, "Failed to tmq_subscribe(): %s\n", tmq_err2str(code));
+    fprintf(stderr, "Failed to subscribe topic_list, ErrCode: 0x%x, ErrMessage: %s.\n", code, tmq_err2str(code));
+  } else {
+    fprintf(stdout, "Subscribe topics successfully.\n");
   }
 
   tmq_list_destroy(topic_list);
@@ -393,13 +431,15 @@ int main(int argc, char* argv[]) {
   // unsubscribe the topic
   code = tmq_unsubscribe(tmq);
   if (code) {
-    fprintf(stderr, "Failed to tmq_unsubscribe(): %s\n", tmq_err2str(code));
+    fprintf(stderr, "Failed to unsubscribe consumer, ErrCode: 0x%x, ErrMessage: %s.\n", code, tmq_err2str(code));
+  } else {
+    fprintf(stderr, "Consumer unsubscribed successfully.\n");
   }
-  fprintf(stderr, "Unsubscribed consumer successfully.\n");
+
   // close the consumer
   code = tmq_consumer_close(tmq);
   if (code) {
-    fprintf(stderr, "Failed to close consumer: %s\n", tmq_err2str(code));
+    fprintf(stderr, "Failed to close consumer: %s.\n", tmq_err2str(code));
   } else {
     fprintf(stderr, "Consumer closed successfully.\n");
   }
diff --git a/docs/examples/c/with_reqid_demo.c b/docs/examples/c/with_reqid_demo.c
index 50d29805f9..724b682850 100644
--- a/docs/examples/c/with_reqid_demo.c
+++ b/docs/examples/c/with_reqid_demo.c
@@ -23,55 +23,59 @@
 #include "taos.h"
 
 static int DemoWithReqId() {
-  // ANCHOR: with_reqid
-  const char *ip = "localhost";
-  const char *user = "root";
-  const char *password = "taosdata";
+// ANCHOR: with_reqid
+const char *host      = "localhost";
+const char *user      = "root";
+const char *password  = "taosdata";
+uint16_t    port      = 6030;
+int code  = 0;
 
-  // connect
-  TAOS *taos = taos_connect(ip, user, password, NULL, 0);
-  if (taos == NULL) {
-    printf("failed to connect to server %s, reason: %s\n", ip, taos_errstr(NULL));
-    taos_cleanup();
-    return -1;
-  }
-  printf("success to connect server %s\n", ip);
-
-  const char *sql = "SELECT ts, current, location FROM power.meters limit 1";
-  // query data with reqid
-  TAOS_RES *result = taos_query_with_reqid(taos, sql, 3L);
-  int       code = taos_errno(result);
-  if (code != 0) {
-    printf("failed to query data from power.meters, ip: %s, reason: %s\n", ip, taos_errstr(result));
-    taos_close(taos);
-    taos_cleanup();
-    return -1;
-  }
-
-  TAOS_ROW    row = NULL;
-  int         rows = 0;
-  int         num_fields = taos_field_count(result);
-  TAOS_FIELD *fields = taos_fetch_fields(result);
-
-  printf("fields: %d\n", num_fields);
-  printf("sql: %s, result:\n", sql);
-
-  // fetch the records row by row
-  while ((row = taos_fetch_row(result))) {
-    char temp[1024] = {0};
-    rows++;
-    taos_print_row(temp, row, fields, num_fields);
-    printf("%s\n", temp);
-  }
-  printf("total rows: %d\n", rows);
-  taos_free_result(result);
-  printf("success to query data from power.meters\n");
-
-  // close & clean
-  taos_close(taos);
+// connect
+TAOS *taos = taos_connect(host, user, password, NULL, port);
+if (taos == NULL) {
+  printf("Failed to connect to %s:%hu, ErrCode: 0x%x, ErrMessage: %s.\n", host, port, taos_errno(NULL), taos_errstr(NULL));
   taos_cleanup();
-  return 0;
-  // ANCHOR_END: with_reqid
+  return -1;
+}
+
+const char *sql = "SELECT ts, current, location FROM power.meters limit 1";
+// query data with reqid
+long reqid = 3L;
+TAOS_RES *result = taos_query_with_reqid(taos, sql, reqid);
+code = taos_errno(result);
+if (code != 0) {
+  printf("Failed to execute sql with reqId: %ld, Server: %s:%hu, ErrCode: 0x%x, ErrMessage: %s\n.", reqid, host, port, code, taos_errstr(result));
+  taos_close(taos);
+  taos_cleanup();
+  return -1;
+}
+
+TAOS_ROW    row         = NULL;
+int         rows        = 0;
+int         num_fields  = taos_field_count(result);
+TAOS_FIELD *fields      = taos_fetch_fields(result);
+
+printf("fields: %d\n", num_fields);
+printf("sql: %s, result:\n", sql);
+
+// fetch the records row by row
+while ((row = taos_fetch_row(result))) {
+  char temp[1024] = {0};
+  rows++;
+  taos_print_row(temp, row, fields, num_fields);
+  printf("%s\n", temp);
+}
+printf("total rows: %d\n", rows);
+taos_free_result(result);
+
+// close & clean
+taos_close(taos);
+taos_cleanup();
+return 0;
+// ANCHOR_END: with_reqid
+}
+
+int main(int argc, char *argv[]) {
+  return DemoWithReqId();
 }
 
-int main(int argc, char *argv[]) { return DemoWithReqId(); }
diff --git a/docs/examples/go/sqlquery/main.go b/docs/examples/go/sqlquery/main.go
index e03c2a14c4..1301c79325 100644
--- a/docs/examples/go/sqlquery/main.go
+++ b/docs/examples/go/sqlquery/main.go
@@ -35,7 +35,7 @@ func main() {
 	}
 	rowsAffected, err = res.RowsAffected()
 	if err != nil {
-		log.Fatalln("Failed to get create create rowsAffected, url:" + taosDSN + "; ErrMessage: " + err.Error())
+		log.Fatalln("Failed to get create db rowsAffected, url:" + taosDSN + "; ErrMessage: " + err.Error())
 	}
 	// you can check rowsAffected here
 	fmt.Println("Create stable power.meters successfully, rowsAffected:", rowsAffected)
@@ -66,7 +66,7 @@ func main() {
 	// query data, make sure the database and table are created before
 	rows, err := db.Query("SELECT ts, current, location FROM power.meters limit 100")
 	if err != nil {
-		log.Fatal("query data failed:", err)
+		log.Fatal("Failed to query data from power.meters, url:" + taosDSN + "; ErrMessage: " + err.Error())
 	}
 	for rows.Next() {
 		var (
@@ -76,7 +76,7 @@ func main() {
 		)
 		err = rows.Scan(&ts, &current, &location)
 		if err != nil {
-			log.Fatal("scan data failed:", err)
+			log.Fatal("Failed to scan data, url:" + taosDSN + "; ErrMessage: " + err.Error())
 		}
 		// you can check data here
 		fmt.Printf("ts: %s, current: %f, location: %s\n", ts, current, location)
diff --git a/docs/examples/rust/nativeexample/examples/tmq.rs b/docs/examples/rust/nativeexample/examples/tmq.rs
index 4ae71bc445..7f3bd416d1 100644
--- a/docs/examples/rust/nativeexample/examples/tmq.rs
+++ b/docs/examples/rust/nativeexample/examples/tmq.rs
@@ -61,7 +61,7 @@ async fn main() -> anyhow::Result<()> {
 
     // ANCHOR: consume
     match consumer.subscribe(["topic_meters"]).await{
-        Ok(_) => println!("subscribe topics successfully."),
+        Ok(_) => println!("Subscribe topics successfully."),
         Err(err) => {
             eprintln!("Failed to subscribe topic_meters, dsn: {}; ErrMessage: {}", dsn, err);
             return Err(err.into());
@@ -123,7 +123,7 @@ async fn main() -> anyhow::Result<()> {
             }
             // commit offset manually when you have processed the message.
             match consumer.commit(offset).await{
-                Ok(_) => println!("commit offset manually successfully."),
+                Ok(_) => println!("Commit offset manually successfully."),
                 Err(err) => {
                     eprintln!("Failed to commit offset manually, dsn: {}; ErrMessage: {}", dsn, err);
                     return Err(err.into());
@@ -140,7 +140,7 @@ async fn main() -> anyhow::Result<()> {
 
     // ANCHOR: seek_offset
     let assignments = consumer.assignments().await.unwrap();
-    println!("assignments: {:?}", assignments);
+    println!("Now assignments: {:?}", assignments);
 
     // seek offset
     for topic_vec_assignment in assignments {
@@ -163,23 +163,24 @@ async fn main() -> anyhow::Result<()> {
             match consumer.offset_seek(topic, vgroup_id, begin).await{
                 Ok(_) => (),
                 Err(err) => {
-                    eprintln!("seek example failed; ErrMessage: {}", err);
+                    eprintln!("Seek example failed; ErrMessage: {}", err);
                     return Err(err.into());
                 }
             }
         }
 
         let topic_assignment = consumer.topic_assignment(topic).await;
-        println!("topic assignment: {:?}", topic_assignment);
+        println!("Topic assignment: {:?}", topic_assignment);
     }
-    println!("assignment seek to beginning successfully.");
+    println!("Assignment seek to beginning successfully.");
     // after seek offset
     let assignments = consumer.assignments().await.unwrap();
-    println!("after seek offset assignments: {:?}", assignments);
+    println!("After seek offset assignments: {:?}", assignments);
     // ANCHOR_END: seek_offset
 
     // ANCHOR: unsubscribe
     consumer.unsubscribe().await;
+    println!("Consumer unsubscribed successfully.");
     // ANCHOR_END: unsubscribe
 
     tokio::time::sleep(Duration::from_secs(1)).await;
diff --git a/docs/examples/rust/restexample/examples/tmq.rs b/docs/examples/rust/restexample/examples/tmq.rs
index c828bd91ac..2abc0a36da 100644
--- a/docs/examples/rust/restexample/examples/tmq.rs
+++ b/docs/examples/rust/restexample/examples/tmq.rs
@@ -61,7 +61,7 @@ async fn main() -> anyhow::Result<()> {
 
     // ANCHOR: consume
     match consumer.subscribe(["topic_meters"]).await{
-        Ok(_) => println!("subscribe topics successfully."),
+        Ok(_) => println!("Subscribe topics successfully."),
         Err(err) => {
             eprintln!("Failed to subscribe topic_meters, dsn: {}; ErrMessage: {}", dsn, err);
             return Err(err.into());
@@ -123,7 +123,7 @@ async fn main() -> anyhow::Result<()> {
             }
             // commit offset manually when you have processed the message.
             match consumer.commit(offset).await{
-                Ok(_) => println!("commit offset manually successfully."),
+                Ok(_) => println!("Commit offset manually successfully."),
                 Err(err) => {
                     eprintln!("Failed to commit offset manually, dsn: {}; ErrMessage: {}", dsn, err);
                     return Err(err.into());
@@ -172,15 +172,15 @@ async fn main() -> anyhow::Result<()> {
         let topic_assignment = consumer.topic_assignment(topic).await;
         println!("topic assignment: {:?}", topic_assignment);
     }
-    println!("assignment seek to beginning successfully.");
+    println!("Assignment seek to beginning successfully.");
     // after seek offset
     let assignments = consumer.assignments().await.unwrap();
-    println!("after seek offset assignments: {:?}", assignments);
+    println!("After seek offset assignments: {:?}", assignments);
     // ANCHOR_END: seek_offset
 
     // ANCHOR: unsubscribe
     consumer.unsubscribe().await;
-    println!("consumer unsubscribed successfully.");
+    println!("Consumer unsubscribed successfully.");
     // ANCHOR_END: unsubscribe
 
     tokio::time::sleep(Duration::from_secs(1)).await;
diff --git a/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/ConsumerLoopFull.java b/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/ConsumerLoopFull.java
index 39782e787c..3c0798d198 100644
--- a/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/ConsumerLoopFull.java
+++ b/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/ConsumerLoopFull.java
@@ -59,7 +59,7 @@ public class ConsumerLoopFull {
 
             // subscribe to the topics
             consumer.subscribe(topics);
-            System.out.println("subscribe topics successfully.");
+            System.out.println("Subscribe topics successfully.");
             for (int i = 0; i < 50; i++) {
                 // poll data
                 ConsumerRecords<ResultBean> records = consumer.poll(Duration.ofMillis(100));
@@ -88,9 +88,9 @@ public class ConsumerLoopFull {
 
             // subscribe to the topics
             consumer.subscribe(topics);
-            System.out.println("subscribe topics successfully.");
+            System.out.println("Subscribe topics successfully.");
             Set<TopicPartition> assignment = consumer.assignment();
-            System.out.println("now assignment: " + JSON.toJSONString(assignment));
+            System.out.println("Now assignment: " + JSON.toJSONString(assignment));
 
             ConsumerRecords<ResultBean> records = ConsumerRecords.emptyRecord();
             // make sure we have got some data
@@ -99,13 +99,13 @@ public class ConsumerLoopFull {
             }
 
             consumer.seekToBeginning(assignment);
-            System.out.println("assignment seek to beginning successfully.");
+            System.out.println("Assignment seek to beginning successfully.");
         } catch (SQLException ex) {
             // handle any errors, please refer to the JDBC specifications for detailed exceptions info
-            System.out.println("seek example failed; ErrCode:" + ex.getErrorCode() + "; ErrMessage: " + ex.getMessage());
+            System.out.println("Seek example failed; ErrCode:" + ex.getErrorCode() + "; ErrMessage: " + ex.getMessage());
             throw new SQLException("seek example failed", ex);
         } catch (Exception ex) {
-            System.out.println("seek example failed; ErrMessage: " + ex.getMessage());
+            System.out.println("Seek example failed; ErrMessage: " + ex.getMessage());
             throw new SQLException("seek example failed", ex);
         }
 // ANCHOR_END: consumer_seek
@@ -128,7 +128,7 @@ public class ConsumerLoopFull {
                 if (!records.isEmpty()) {
                     // after processing the data, commit the offset manually
                     consumer.commitSync();
-                    System.out.println("commit offset manually successfully.");
+                    System.out.println("Commit offset manually successfully.");
                 }
             }
         } catch (SQLException ex) {
@@ -149,7 +149,7 @@ public class ConsumerLoopFull {
         try {
             // unsubscribe the consumer
             consumer.unsubscribe();
-            System.out.println("consumer unsubscribed successfully.");
+            System.out.println("Consumer unsubscribed successfully.");
         } catch (SQLException ex) {
             // handle any errors, please refer to the JDBC specifications for detailed exceptions info
             System.out.println("Failed to unsubscribe consumer. ErrCode:" + ex.getErrorCode() + "; ErrMessage: " + ex.getMessage());
@@ -161,7 +161,7 @@ public class ConsumerLoopFull {
         finally {
             // close the consumer
             consumer.close();
-            System.out.println("consumer closed successfully.");
+            System.out.println("Consumer closed successfully.");
         }
 // ANCHOR_END: unsubscribe_data_code_piece
     }
diff --git a/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/WsConsumerLoopFull.java b/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/WsConsumerLoopFull.java
index 45767f8461..d7207ffe71 100644
--- a/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/WsConsumerLoopFull.java
+++ b/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/WsConsumerLoopFull.java
@@ -57,7 +57,7 @@ public class WsConsumerLoopFull {
 
             // subscribe to the topics
             consumer.subscribe(topics);
-            System.out.println("subscribe topics successfully.");
+            System.out.println("Subscribe topics successfully.");
             for (int i = 0; i < 50; i++) {
                 // poll data
                 ConsumerRecords<ResultBean> records = consumer.poll(Duration.ofMillis(100));
@@ -86,9 +86,9 @@ public class WsConsumerLoopFull {
 
             // subscribe to the topics
             consumer.subscribe(topics);
-            System.out.println("subscribe topics successfully.");
+            System.out.println("Subscribe topics successfully.");
             Set<TopicPartition> assignment = consumer.assignment();
-            System.out.println("now assignment: " + JSON.toJSONString(assignment));
+            System.out.println("Now assignment: " + JSON.toJSONString(assignment));
 
             ConsumerRecords<ResultBean> records = ConsumerRecords.emptyRecord();
             // make sure we have got some data
@@ -97,13 +97,13 @@ public class WsConsumerLoopFull {
             }
 
             consumer.seekToBeginning(assignment);
-            System.out.println("assignment seek to beginning successfully.");
+            System.out.println("Assignment seek to beginning successfully.");
         } catch (SQLException ex) {
             // handle any errors, please refer to the JDBC specifications for detailed exceptions info
-            System.out.println("seek example failed; ErrCode:" + ex.getErrorCode() + "; ErrMessage: " + ex.getMessage());
+            System.out.println("Seek example failed; ErrCode:" + ex.getErrorCode() + "; ErrMessage: " + ex.getMessage());
             throw new SQLException("seek example failed", ex);
         } catch (Exception ex) {
-            System.out.println("seek example failed; ErrMessage: " + ex.getMessage());
+            System.out.println("Seek example failed; ErrMessage: " + ex.getMessage());
             throw new SQLException("seek example failed", ex);
         }
 // ANCHOR_END: consumer_seek
@@ -126,7 +126,7 @@ public class WsConsumerLoopFull {
                 if (!records.isEmpty()) {
                     // after processing the data, commit the offset manually
                     consumer.commitSync();
-                    System.out.println("commit offset manually successfully.");
+                    System.out.println("Commit offset manually successfully.");
                 }
             }
         } catch (SQLException ex) {
@@ -147,7 +147,7 @@ public class WsConsumerLoopFull {
         try {
             // unsubscribe the consumer
             consumer.unsubscribe();
-            System.out.println("consumer unsubscribed successfully.");
+            System.out.println("Consumer unsubscribed successfully.");
         } catch (SQLException ex) {
             // handle any errors, please refer to the JDBC specifications for detailed exceptions info
             System.out.println("Failed to unsubscribe consumer. ErrCode:" + ex.getErrorCode() + "; ErrMessage: " + ex.getMessage());
@@ -159,7 +159,7 @@ public class WsConsumerLoopFull {
         finally {
             // close the consumer
             consumer.close();
-            System.out.println("consumer closed successfully.");
+            System.out.println("Consumer closed successfully.");
         }
 // ANCHOR_END: unsubscribe_data_code_piece
     }