C/C++ Connector

C/C++ 开发人员可以使用 TDengine 的客户端驱动，即 C/C++连接器（以下都用 TDengine 客户端驱动表示），开发自己的应用来连接 TDengine 集群完成数据存储、查询以及其他功能。TDengine 客户端驱动的 API 类似于 MySQL 的 C API。应用程序使用时，需要包含 TDengine 头文件 taos.h，里面列出了提供的 API 的函数原型；应用程序还要链接到所在平台上对应的动态库。

#include <taos.h>

TDengine 服务端或客户端安装后，taos.h 位于：

Linux：/usr/local/taos/include
Windows：C:\TDengine\include

TDengine 客户端驱动的动态库位于：

Linux: /usr/local/taos/driver/libtaos.so
Windows: C:\TDengine\taos.dll

支持的平台

请参考支持的平台列表

支持的版本

TDengine 客户端驱动的版本号与 TDengine 服务端的版本号是一一对应的强对应关系，建议使用与 TDengine 服务端完全相同的客户端驱动。虽然低版本的客户端驱动在前三段版本号一致（即仅第四段版本号不同）的情况下也能够与高版本的服务端相兼容，但这并非推荐用法。强烈不建议使用高版本的客户端驱动访问低版本的服务端。

安装步骤

TDengine 客户端驱动的安装请参考安装指南

建立连接

使用客户端驱动访问 TDengine 集群的基本过程为：建立连接、查询和写入、关闭连接、清除资源。

下面为建立连接的示例代码，其中省略了查询和写入部分，展示了如何建立连接、关闭连接以及清除资源。

  TAOS *taos = taos_connect("localhost:6030", "root", "taosdata", NULL, 0);
  if (taos == NULL) {
    printf("failed to connect to server, reason:%s\n", "null taos" /*taos_errstr(taos)*/);
    exit(1);
  }

  /* put your code here for read and write */

  taos_close(taos);
  taos_cleanup();

在上面的示例代码中， taos_connect() 建立到客户端程序所在主机的 6030 端口的连接，taos_close()关闭当前连接，taos_cleanup()清除客户端驱动所申请和使用的资源。

note

如未特别说明，当 API 的返回值是整数时，0 代表成功，其它是代表失败原因的错误码，当返回值是指针时， NULL 表示失败。
所有的错误码以及对应的原因描述在 taoserror.h 文件中。

示例程序

本节展示了使用客户端驱动访问 TDengine 集群的常见访问方式的示例代码。

同步查询示例

同步查询

/*
 * 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 demo demo.c -ltaos

#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <taos.h>  // TAOS header file

static void queryDB(TAOS *taos, char *command) {
  int       i;
  TAOS_RES *pSql = NULL;
  int32_t   code = -1;

  for (i = 0; i < 5; i++) {
    if (NULL != pSql) {
      taos_free_result(pSql);
      pSql = NULL;
    }

    pSql = taos_query(taos, command);
    code = taos_errno(pSql);
    if (0 == code) {
      break;
    }
  }

  if (code != 0) {
    fprintf(stderr, "Failed to run %s, reason: %s\n", command, taos_errstr(pSql));
    taos_free_result(pSql);
    taos_close(taos);
    exit(EXIT_FAILURE);
  }

  taos_free_result(pSql);
}

void Test(TAOS *taos, char *qstr, int i);

int main(int argc, char *argv[]) {
  char qstr[1024];

  // 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);
  }
  for (int i = 0; i < 100; i++) {
    Test(taos, qstr, i);
  }
  taos_close(taos);
  taos_cleanup();
}
void Test(TAOS *taos, char *qstr, int index) {
  printf("==================test at %d\n================================", index);
  queryDB(taos, "drop database if exists demo");
  queryDB(taos, "create database demo");
  TAOS_RES *result;
  queryDB(taos, "use demo");

  queryDB(taos,
          "create table m1 (ts timestamp, ti tinyint, si smallint, i int, bi bigint, f float, d double, b binary(10))");
  printf("success to create table\n");

  int i = 0;
  for (i = 0; i < 10; ++i) {
    sprintf(qstr, "insert into m1 values (%" PRId64 ", %d, %d, %d, %d, %f, %lf, '%s')",
            (uint64_t)(1546300800000 + i * 1000), i, i, i, i * 10000000, i * 1.0, i * 2.0, "hello");
    printf("qstr: %s\n", qstr);

    // note: how do you wanna do if taos_query returns non-NULL
    // if (taos_query(taos, qstr)) {
    //   printf("insert row: %i, reason:%s\n", i, taos_errstr(taos));
    // }
    TAOS_RES *result1 = taos_query(taos, qstr);
    if (result1 == NULL || taos_errno(result1) != 0) {
      printf("failed to insert row, reason:%s\n", taos_errstr(result1));
      taos_free_result(result1);
      exit(1);
    } else {
      printf("insert row: %i\n", i);
    }
    taos_free_result(result1);
  }
  printf("success to insert rows, total %d rows\n", i);

  // query the records
  sprintf(qstr, "SELECT * FROM m1");
  result = taos_query(taos, qstr);
  if (result == NULL || taos_errno(result) != 0) {
    printf("failed to select, reason:%s\n", taos_errstr(result));
    taos_free_result(result);
    exit(1);
  }

  TAOS_ROW    row;
  int         rows = 0;
  int         num_fields = taos_field_count(result);
  TAOS_FIELD *fields = taos_fetch_fields(result);

  printf("num_fields = %d\n", num_fields);
  printf("select * from table, result:\n");
  // 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);
  }

  taos_free_result(result);
  printf("====demo end====\n\n");
}

查看源码

异步查询示例

异步查询

/*
 * 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 asynchronous API example
// this example opens multiple tables, insert/retrieve multiple tables
// it is used by TAOS internally for one performance testing
// to compiple: gcc -o asyncdemo asyncdemo.c -ltaos

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>

#include <taos.h>

int     points = 5;
int     numOfTables = 3;
int     tablesInsertProcessed = 0;
int     tablesSelectProcessed = 0;
int64_t st, et;

typedef struct {
  int    id;
  TAOS * taos;
  char   name[16];
  time_t timeStamp;
  int    value;
  int    rowsInserted;
  int    rowsTried;
  int    rowsRetrieved;
} STable;

void taos_insert_call_back(void *param, TAOS_RES *tres, int code);
void taos_select_call_back(void *param, TAOS_RES *tres, int code);
void taos_error(TAOS *taos);

static void queryDB(TAOS *taos, char *command) {
  int       i;
  TAOS_RES *pSql = NULL;
  int32_t   code = -1;

  for (i = 0; i < 5; i++) {
    if (NULL != pSql) {
      taos_free_result(pSql);
      pSql = NULL;
    }

    pSql = taos_query(taos, command);
    code = taos_errno(pSql);
    if (0 == code) {
      break;
    }
  }

  if (code != 0) {
    fprintf(stderr, "Failed to run %s, reason: %s\n", command, taos_errstr(pSql));
    taos_free_result(pSql);
    taos_close(taos);
    taos_cleanup();
    exit(EXIT_FAILURE);
  }

  taos_free_result(pSql);
}

int main(int argc, char *argv[]) {
  TAOS *         taos;
  struct timeval systemTime;
  int            i;
  char           sql[1024] = {0};
  char           prefix[20] = {0};
  char           db[128] = {0};
  STable *       tableList;

  if (argc != 5) {
    printf("usage: %s server-ip dbname rowsPerTable numOfTables\n", argv[0]);
    exit(0);
  }

  // a simple way to parse input parameters
  if (argc >= 3) strcpy(db, argv[2]);
  if (argc >= 4) points = atoi(argv[3]);
  if (argc >= 5) numOfTables = atoi(argv[4]);

  size_t size = sizeof(STable) * (size_t)numOfTables;
  tableList = (STable *)malloc(size);
  memset(tableList, 0, size);

  taos = taos_connect(argv[1], "root", "taosdata", NULL, 0);
  if (taos == NULL) taos_error(taos);

  printf("success to connect to server\n");

  sprintf(sql, "drop database if exists %s", db);
  queryDB(taos, sql);

  sprintf(sql, "create database %s", db);
  queryDB(taos, sql);

  sprintf(sql, "use %s", db);
  queryDB(taos, sql);

  strcpy(prefix, "asytbl_");
  for (i = 0; i < numOfTables; ++i) {
    tableList[i].id = i;
    tableList[i].taos = taos;
    sprintf(tableList[i].name, "%s%d", prefix, i);
    sprintf(sql, "create table %s%d (ts timestamp, volume bigint)", prefix, i);
    queryDB(taos, sql);
  }

  gettimeofday(&systemTime, NULL);
  for (i = 0; i < numOfTables; ++i)
    tableList[i].timeStamp = (time_t)(systemTime.tv_sec) * 1000 + systemTime.tv_usec / 1000;

  printf("success to create tables, press any key to insert\n");
  getchar();

  printf("start to insert...\n");
  gettimeofday(&systemTime, NULL);
  st = systemTime.tv_sec * 1000000 + systemTime.tv_usec;

  tablesInsertProcessed = 0;
  tablesSelectProcessed = 0;

  for (i = 0; i < numOfTables; ++i) {
    // insert records in asynchronous API
    sprintf(sql, "insert into %s values(%ld, 0)", tableList[i].name, 1546300800000 + i);
    taos_query_a(taos, sql, taos_insert_call_back, (void *)(tableList + i));
  }

  printf("once insert finished, presse any key to query\n");
  getchar();

  while (1) {
    if (tablesInsertProcessed < numOfTables) {
      printf("wait for process finished\n");
      sleep(1);
      continue;
    }

    break;
  }

  printf("start to query...\n");
  gettimeofday(&systemTime, NULL);
  st = systemTime.tv_sec * 1000000 + systemTime.tv_usec;

  for (i = 0; i < numOfTables; ++i) {
    // select records in asynchronous API
    sprintf(sql, "select * from %s", tableList[i].name);
    taos_query_a(taos, sql, taos_select_call_back, (void *)(tableList + i));
  }

  printf("\nonce finished, press any key to exit\n");
  getchar();

  while (1) {
    if (tablesSelectProcessed < numOfTables) {
      printf("wait for process finished\n");
      sleep(1);
      continue;
    }

    break;
  }

  for (i = 0; i < numOfTables; ++i) {
    printf("%s inserted:%d retrieved:%d\n", tableList[i].name, tableList[i].rowsInserted, tableList[i].rowsRetrieved);
  }

  taos_close(taos);
  free(tableList);

  printf("==== async demo end====\n");
  printf("\n");
  return 0;
}

void taos_error(TAOS *con) {
  fprintf(stderr, "TDengine error: %s\n", taos_errstr(con));
  taos_close(con);
  taos_cleanup();
  exit(1);
}

void taos_insert_call_back(void *param, TAOS_RES *tres, int code) {
  STable *       pTable = (STable *)param;
  struct timeval systemTime;
  char           sql[128];

  pTable->rowsTried++;

  if (code < 0) {
    printf("%s insert failed, code:%d, rows:%d\n", pTable->name, code, pTable->rowsTried);
  } else if (code == 0) {
    printf("%s not inserted\n", pTable->name);
  } else {
    pTable->rowsInserted++;
  }

  if (pTable->rowsTried < points) {
    // for this demo, insert another record
    sprintf(sql, "insert into %s values(%ld, %d)", pTable->name, 1546300800000 + pTable->rowsTried * 1000,
            pTable->rowsTried);
    taos_query_a(pTable->taos, sql, taos_insert_call_back, (void *)pTable);
  } else {
    printf("%d rows data are inserted into %s\n", points, pTable->name);
    tablesInsertProcessed++;
    if (tablesInsertProcessed >= numOfTables) {
      gettimeofday(&systemTime, NULL);
      et = systemTime.tv_sec * 1000000 + systemTime.tv_usec;
      printf("%lld mseconds to insert %d data points\n", (et - st) / 1000, points * numOfTables);
    }
  }

  taos_free_result(tres);
}

void taos_retrieve_call_back(void *param, TAOS_RES *tres, int numOfRows) {
  STable *       pTable = (STable *)param;
  struct timeval systemTime;

  if (numOfRows > 0) {
    for (int i = 0; i < numOfRows; ++i) {
      // synchronous API to retrieve a row from batch of records
      /*TAOS_ROW row = */ (void)taos_fetch_row(tres);
      // process row
    }

    pTable->rowsRetrieved += numOfRows;

    // retrieve next batch of rows
    taos_fetch_rows_a(tres, taos_retrieve_call_back, pTable);

  } else {
    if (numOfRows < 0) printf("%s retrieve failed, code:%d\n", pTable->name, numOfRows);

    // taos_free_result(tres);
    printf("%d rows data retrieved from %s\n", pTable->rowsRetrieved, pTable->name);

    tablesSelectProcessed++;
    if (tablesSelectProcessed >= numOfTables) {
      gettimeofday(&systemTime, NULL);
      et = systemTime.tv_sec * 1000000 + systemTime.tv_usec;
      printf("%lld mseconds to query %d data rows\n", (et - st) / 1000, points * numOfTables);
    }

    taos_free_result(tres);
  }
}

void taos_select_call_back(void *param, TAOS_RES *tres, int code) {
  STable *pTable = (STable *)param;

  if (code == 0 && tres) {
    // asynchronous API to fetch a batch of records
    taos_fetch_rows_a(tres, taos_retrieve_call_back, pTable);
  } else {
    printf("%s select failed, code:%d\n", pTable->name, code);
    taos_free_result(tres);
    taos_cleanup();
    exit(1);
  }
}

查看源码

参数绑定示例

参数绑定

// TAOS standard API example. The same syntax as MySQL, but only a subet
// to compile: gcc -o prepare prepare.c -ltaos

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <taos.h>
#include <unistd.h>

void taosMsleep(int mseconds);

void verify_prepare(TAOS* taos) {
  TAOS_RES* result = taos_query(taos, "drop database if exists test;");
  taos_free_result(result);

  usleep(100000);
  result = taos_query(taos, "create database test;");

  int code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create database, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }

  taos_free_result(result);

  usleep(100000);
  taos_select_db(taos, "test");

  // 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), u1 tinyint unsigned, u2 smallint unsigned, u4 int unsigned, u8 bigint unsigned)";
  result = taos_query(taos, sql);
  code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create table, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }
  taos_free_result(result);

  // insert 10 records
  struct {
    int64_t  ts;
    int8_t   b;
    int8_t   v1;
    int16_t  v2;
    int32_t  v4;
    int64_t  v8;
    float    f4;
    double   f8;
    char     bin[40];
    char     blob[80];
    uint8_t  u1;
    uint16_t u2;
    uint32_t u4;
    uint64_t u8;
  } v = {0};

  TAOS_STMT* stmt = taos_stmt_init(taos);
  TAOS_BIND  params[14];
  params[0].buffer_type = TSDB_DATA_TYPE_TIMESTAMP;
  params[0].buffer_length = sizeof(v.ts);
  params[0].buffer = &v.ts;
  params[0].length = &params[0].buffer_length;
  params[0].is_null = NULL;

  params[1].buffer_type = TSDB_DATA_TYPE_BOOL;
  params[1].buffer_length = sizeof(v.b);
  params[1].buffer = &v.b;
  params[1].length = &params[1].buffer_length;
  params[1].is_null = NULL;

  params[2].buffer_type = TSDB_DATA_TYPE_TINYINT;
  params[2].buffer_length = sizeof(v.v1);
  params[2].buffer = &v.v1;
  params[2].length = &params[2].buffer_length;
  params[2].is_null = NULL;

  params[3].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  params[3].buffer_length = sizeof(v.v2);
  params[3].buffer = &v.v2;
  params[3].length = &params[3].buffer_length;
  params[3].is_null = NULL;

  params[4].buffer_type = TSDB_DATA_TYPE_INT;
  params[4].buffer_length = sizeof(v.v4);
  params[4].buffer = &v.v4;
  params[4].length = &params[4].buffer_length;
  params[4].is_null = NULL;

  params[5].buffer_type = TSDB_DATA_TYPE_BIGINT;
  params[5].buffer_length = sizeof(v.v8);
  params[5].buffer = &v.v8;
  params[5].length = &params[5].buffer_length;
  params[5].is_null = NULL;

  params[6].buffer_type = TSDB_DATA_TYPE_FLOAT;
  params[6].buffer_length = sizeof(v.f4);
  params[6].buffer = &v.f4;
  params[6].length = &params[6].buffer_length;
  params[6].is_null = NULL;

  params[7].buffer_type = TSDB_DATA_TYPE_DOUBLE;
  params[7].buffer_length = sizeof(v.f8);
  params[7].buffer = &v.f8;
  params[7].length = &params[7].buffer_length;
  params[7].is_null = NULL;

  params[8].buffer_type = TSDB_DATA_TYPE_BINARY;
  params[8].buffer_length = sizeof(v.bin);
  params[8].buffer = v.bin;
  params[8].length = &params[8].buffer_length;
  params[8].is_null = NULL;

  strcpy(v.blob, "一二三四五六七八九十");
  params[9].buffer_type = TSDB_DATA_TYPE_NCHAR;
  params[9].buffer_length = strlen(v.blob);
  params[9].buffer = v.blob;
  params[9].length = &params[9].buffer_length;
  params[9].is_null = NULL;

  params[10].buffer_type = TSDB_DATA_TYPE_UTINYINT;
  params[10].buffer_length = sizeof(v.u1);
  params[10].buffer = &v.u1;
  params[10].length = &params[10].buffer_length;
  params[10].is_null = NULL;

  params[11].buffer_type = TSDB_DATA_TYPE_USMALLINT;
  params[11].buffer_length = sizeof(v.u2);
  params[11].buffer = &v.u2;
  params[11].length = &params[11].buffer_length;
  params[11].is_null = NULL;

  params[12].buffer_type = TSDB_DATA_TYPE_UINT;
  params[12].buffer_length = sizeof(v.u4);
  params[12].buffer = &v.u4;
  params[12].length = &params[12].buffer_length;
  params[12].is_null = NULL;

  params[13].buffer_type = TSDB_DATA_TYPE_UBIGINT;
  params[13].buffer_length = sizeof(v.u8);
  params[13].buffer = &v.u8;
  params[13].length = &params[13].buffer_length;
  params[13].is_null = NULL;

  int is_null = 1;

  sql = "insert into m1 values(?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
  code = taos_stmt_prepare(stmt, sql, 0);
  if (code != 0) {
    printf("\033[31mfailed to execute taos_stmt_prepare. error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }
  v.ts = 1591060628000;
  for (int i = 0; i < 10; ++i) {
    v.ts += 1;
    for (int j = 1; j < 10; ++j) {
      params[j].is_null = ((i == j) ? &is_null : 0);
    }
    v.b = (int8_t)i % 2;
    v.v1 = (int8_t)i;
    v.v2 = (int16_t)(i * 2);
    v.v4 = (int32_t)(i * 4);
    v.v8 = (int64_t)(i * 8);
    v.f4 = (float)(i * 40);
    v.f8 = (double)(i * 80);
    for (int j = 0; j < sizeof(v.bin); ++j) {
      v.bin[j] = (char)(i + '0');
    }
    v.u1 = (uint8_t)i;
    v.u2 = (uint16_t)(i * 2);
    v.u4 = (uint32_t)(i * 4);
    v.u8 = (uint64_t)(i * 8);

    taos_stmt_bind_param(stmt, params);
    taos_stmt_add_batch(stmt);
  }
  if (taos_stmt_execute(stmt) != 0) {
    printf("\033[31mfailed to execute insert statement.error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  int affectedRows = taos_stmt_affected_rows(stmt);
  printf("sucessfully inserted %d rows\n", affectedRows);

  taos_stmt_close(stmt);

  // query the records
  stmt = taos_stmt_init(taos);
  taos_stmt_prepare(stmt, "SELECT * FROM m1 WHERE v1 > ? AND v2 < ?", 0);
  v.v1 = 5;
  v.v2 = 15;
  taos_stmt_bind_param(stmt, params + 2);
  if (taos_stmt_execute(stmt) != 0) {
    printf("\033[31mfailed to execute select statement.error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  result = taos_stmt_use_result(stmt);

  TAOS_ROW    row;
  int         rows = 0;
  int         num_fields = taos_num_fields(result);
  TAOS_FIELD* fields = taos_fetch_fields(result);

  // fetch the records row by row
  while ((row = taos_fetch_row(result))) {
    char temp[256] = {0};
    rows++;
    taos_print_row(temp, row, fields, num_fields);
    printf("%s\n", temp);
  }

  taos_free_result(result);
  taos_stmt_close(stmt);
}

void verify_prepare2(TAOS* taos) {
  TAOS_RES* result = taos_query(taos, "drop database if exists test;");
  taos_free_result(result);
  usleep(100000);
  result = taos_query(taos, "create database test;");

  int code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create database, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }
  taos_free_result(result);

  usleep(100000);
  taos_select_db(taos, "test");

  // 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), u1 tinyint unsigned, u2 smallint unsigned, u4 int unsigned, u8 bigint unsigned)";
  result = taos_query(taos, sql);
  code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create table, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }
  taos_free_result(result);

  // insert 10 records
  struct {
    int64_t  ts;
    int8_t   b;
    int8_t   v1;
    int16_t  v2;
    int32_t  v4;
    int64_t  v8;
    float    f4;
    double   f8;
    char     bin[40];
    char     blob[80];
    uint8_t  u1;
    uint16_t u2;
    uint32_t u4;
    uint64_t u8;
  } v = {0};

  TAOS_STMT* stmt = taos_stmt_init(taos);
  TAOS_BIND  params[14];
  params[0].buffer_type = TSDB_DATA_TYPE_TIMESTAMP;
  params[0].buffer_length = sizeof(v.ts);
  params[0].buffer = &v.ts;
  params[0].length = &params[0].buffer_length;
  params[0].is_null = NULL;

  params[1].buffer_type = TSDB_DATA_TYPE_BOOL;
  params[1].buffer_length = sizeof(v.b);
  params[1].buffer = &v.b;
  params[1].length = &params[1].buffer_length;
  params[1].is_null = NULL;

  params[2].buffer_type = TSDB_DATA_TYPE_TINYINT;
  params[2].buffer_length = sizeof(v.v1);
  params[2].buffer = &v.v1;
  params[2].length = &params[2].buffer_length;
  params[2].is_null = NULL;

  params[3].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  params[3].buffer_length = sizeof(v.v2);
  params[3].buffer = &v.v2;
  params[3].length = &params[3].buffer_length;
  params[3].is_null = NULL;

  params[4].buffer_type = TSDB_DATA_TYPE_INT;
  params[4].buffer_length = sizeof(v.v4);
  params[4].buffer = &v.v4;
  params[4].length = &params[4].buffer_length;
  params[4].is_null = NULL;

  params[5].buffer_type = TSDB_DATA_TYPE_BIGINT;
  params[5].buffer_length = sizeof(v.v8);
  params[5].buffer = &v.v8;
  params[5].length = &params[5].buffer_length;
  params[5].is_null = NULL;

  params[6].buffer_type = TSDB_DATA_TYPE_FLOAT;
  params[6].buffer_length = sizeof(v.f4);
  params[6].buffer = &v.f4;
  params[6].length = &params[6].buffer_length;
  params[6].is_null = NULL;

  params[7].buffer_type = TSDB_DATA_TYPE_DOUBLE;
  params[7].buffer_length = sizeof(v.f8);
  params[7].buffer = &v.f8;
  params[7].length = &params[7].buffer_length;
  params[7].is_null = NULL;

  params[8].buffer_type = TSDB_DATA_TYPE_BINARY;
  params[8].buffer_length = sizeof(v.bin);
  params[8].buffer = v.bin;
  params[8].length = &params[8].buffer_length;
  params[8].is_null = NULL;

  strcpy(v.blob, "一二三四五六七八九十");
  params[9].buffer_type = TSDB_DATA_TYPE_NCHAR;
  params[9].buffer_length = strlen(v.blob);
  params[9].buffer = v.blob;
  params[9].length = &params[9].buffer_length;
  params[9].is_null = NULL;

  params[10].buffer_type = TSDB_DATA_TYPE_UTINYINT;
  params[10].buffer_length = sizeof(v.u1);
  params[10].buffer = &v.u1;
  params[10].length = &params[10].buffer_length;
  params[10].is_null = NULL;

  params[11].buffer_type = TSDB_DATA_TYPE_USMALLINT;
  params[11].buffer_length = sizeof(v.u2);
  params[11].buffer = &v.u2;
  params[11].length = &params[11].buffer_length;
  params[11].is_null = NULL;

  params[12].buffer_type = TSDB_DATA_TYPE_UINT;
  params[12].buffer_length = sizeof(v.u4);
  params[12].buffer = &v.u4;
  params[12].length = &params[12].buffer_length;
  params[12].is_null = NULL;

  params[13].buffer_type = TSDB_DATA_TYPE_UBIGINT;
  params[13].buffer_length = sizeof(v.u8);
  params[13].buffer = &v.u8;
  params[13].length = &params[13].buffer_length;
  params[13].is_null = NULL;

  sql = "insert into ? values(?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
  code = taos_stmt_prepare(stmt, sql, 0);
  if (code != 0) {
    printf("\033[31mfailed to execute taos_stmt_prepare. error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  code = taos_stmt_set_tbname(stmt, "m1");
  if (code != 0) {
    printf("\033[31mfailed to execute taos_stmt_prepare. error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  int is_null = 1;

  v.ts = 1591060628000;
  for (int i = 0; i < 10; ++i) {
    v.ts += 1;
    for (int j = 1; j < 10; ++j) {
      params[j].is_null = ((i == j) ? &is_null : 0);
    }
    v.b = (int8_t)i % 2;
    v.v1 = (int8_t)i;
    v.v2 = (int16_t)(i * 2);
    v.v4 = (int32_t)(i * 4);
    v.v8 = (int64_t)(i * 8);
    v.f4 = (float)(i * 40);
    v.f8 = (double)(i * 80);
    for (int j = 0; j < sizeof(v.bin); ++j) {
      v.bin[j] = (char)(i + '0');
    }
    v.u1 = (uint8_t)i;
    v.u2 = (uint16_t)(i * 2);
    v.u4 = (uint32_t)(i * 4);
    v.u8 = (uint64_t)(i * 8);

    taos_stmt_bind_param(stmt, params);
    taos_stmt_add_batch(stmt);
  }

  if (taos_stmt_execute(stmt) != 0) {
    printf("\033[31mfailed to execute insert statement.error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  int affectedRows = taos_stmt_affected_rows(stmt);
  printf("sucessfully inserted %d rows\n", affectedRows);

  taos_stmt_close(stmt);

  // query the records
  stmt = taos_stmt_init(taos);
  taos_stmt_prepare(stmt, "SELECT * FROM m1 WHERE v1 > ? AND v2 < ?", 0);
  TAOS_BIND qparams[2];

  int8_t  v1 = 5;
  int16_t v2 = 15;
  qparams[0].buffer_type = TSDB_DATA_TYPE_TINYINT;
  qparams[0].buffer_length = sizeof(v1);
  qparams[0].buffer = &v1;
  qparams[0].length = &qparams[0].buffer_length;
  qparams[0].is_null = NULL;

  qparams[1].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  qparams[1].buffer_length = sizeof(v2);
  qparams[1].buffer = &v2;
  qparams[1].length = &qparams[1].buffer_length;
  qparams[1].is_null = NULL;

  taos_stmt_bind_param(stmt, qparams);
  if (taos_stmt_execute(stmt) != 0) {
    printf("\033[31mfailed to execute select statement.error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  result = taos_stmt_use_result(stmt);

  TAOS_ROW    row;
  int         rows = 0;
  int         num_fields = taos_num_fields(result);
  TAOS_FIELD* fields = taos_fetch_fields(result);

  // fetch the records row by row
  while ((row = taos_fetch_row(result))) {
    char temp[256] = {0};
    rows++;
    taos_print_row(temp, row, fields, num_fields);
    printf("%s\n", temp);
  }

  taos_free_result(result);
  taos_stmt_close(stmt);
}

void verify_prepare3(TAOS* taos) {
  TAOS_RES* result = taos_query(taos, "drop database if exists test;");
  taos_free_result(result);
  usleep(100000);
  result = taos_query(taos, "create database test;");

  int code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create database, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }
  taos_free_result(result);

  usleep(100000);
  taos_select_db(taos, "test");

  // create table
  const char* sql =
      "create stable st1 (ts timestamp, b bool, v1 tinyint, v2 smallint, v4 int, v8 bigint, f4 float, f8 double, bin "
      "binary(40), blob nchar(10), u1 tinyint unsigned, u2 smallint unsigned, u4 int unsigned, u8 bigint unsigned) "
      "tags "
      "(b_tag bool, v1_tag tinyint, v2_tag smallint, v4_tag int, v8_tag bigint, f4_tag float, f8_tag double, bin_tag "
      "binary(40), blob_tag nchar(10), u1_tag tinyint unsigned, u2_tag smallint unsigned, u4_tag int unsigned, u8_tag "
      "bigint "
      "unsigned)";
  result = taos_query(taos, sql);
  code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create table, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }
  taos_free_result(result);

  TAOS_BIND tags[13];

  struct {
    int8_t   b;
    int8_t   v1;
    int16_t  v2;
    int32_t  v4;
    int64_t  v8;
    float    f4;
    double   f8;
    char     bin[40];
    char     blob[80];
    uint8_t  u1;
    uint16_t u2;
    uint32_t u4;
    uint64_t u8;
  } id = {0};

  id.b = (int8_t)1;
  id.v1 = (int8_t)1;
  id.v2 = (int16_t)2;
  id.v4 = (int32_t)4;
  id.v8 = (int64_t)8;
  id.f4 = (float)40;
  id.f8 = (double)80;
  for (int j = 0; j < sizeof(id.bin); ++j) {
    id.bin[j] = (char)('1' + '0');
  }
  strcpy(id.blob, "一二三四五六七八九十");
  id.u1 = (uint8_t)1;
  id.u2 = (uint16_t)2;
  id.u4 = (uint32_t)4;
  id.u8 = (uint64_t)8;

  tags[0].buffer_type = TSDB_DATA_TYPE_BOOL;
  tags[0].buffer_length = sizeof(id.b);
  tags[0].buffer = &id.b;
  tags[0].length = &tags[0].buffer_length;
  tags[0].is_null = NULL;

  tags[1].buffer_type = TSDB_DATA_TYPE_TINYINT;
  tags[1].buffer_length = sizeof(id.v1);
  tags[1].buffer = &id.v1;
  tags[1].length = &tags[1].buffer_length;
  tags[1].is_null = NULL;

  tags[2].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  tags[2].buffer_length = sizeof(id.v2);
  tags[2].buffer = &id.v2;
  tags[2].length = &tags[2].buffer_length;
  tags[2].is_null = NULL;

  tags[3].buffer_type = TSDB_DATA_TYPE_INT;
  tags[3].buffer_length = sizeof(id.v4);
  tags[3].buffer = &id.v4;
  tags[3].length = &tags[3].buffer_length;
  tags[3].is_null = NULL;

  tags[4].buffer_type = TSDB_DATA_TYPE_BIGINT;
  tags[4].buffer_length = sizeof(id.v8);
  tags[4].buffer = &id.v8;
  tags[4].length = &tags[4].buffer_length;
  tags[4].is_null = NULL;

  tags[5].buffer_type = TSDB_DATA_TYPE_FLOAT;
  tags[5].buffer_length = sizeof(id.f4);
  tags[5].buffer = &id.f4;
  tags[5].length = &tags[5].buffer_length;
  tags[5].is_null = NULL;

  tags[6].buffer_type = TSDB_DATA_TYPE_DOUBLE;
  tags[6].buffer_length = sizeof(id.f8);
  tags[6].buffer = &id.f8;
  tags[6].length = &tags[6].buffer_length;
  tags[6].is_null = NULL;

  tags[7].buffer_type = TSDB_DATA_TYPE_BINARY;
  tags[7].buffer_length = sizeof(id.bin);
  tags[7].buffer = &id.bin;
  tags[7].length = &tags[7].buffer_length;
  tags[7].is_null = NULL;

  tags[8].buffer_type = TSDB_DATA_TYPE_NCHAR;
  tags[8].buffer_length = strlen(id.blob);
  tags[8].buffer = &id.blob;
  tags[8].length = &tags[8].buffer_length;
  tags[8].is_null = NULL;

  tags[9].buffer_type = TSDB_DATA_TYPE_UTINYINT;
  tags[9].buffer_length = sizeof(id.u1);
  tags[9].buffer = &id.u1;
  tags[9].length = &tags[9].buffer_length;
  tags[9].is_null = NULL;

  tags[10].buffer_type = TSDB_DATA_TYPE_USMALLINT;
  tags[10].buffer_length = sizeof(id.u2);
  tags[10].buffer = &id.u2;
  tags[10].length = &tags[10].buffer_length;
  tags[10].is_null = NULL;

  tags[11].buffer_type = TSDB_DATA_TYPE_UINT;
  tags[11].buffer_length = sizeof(id.u4);
  tags[11].buffer = &id.u4;
  tags[11].length = &tags[11].buffer_length;
  tags[11].is_null = NULL;

  tags[12].buffer_type = TSDB_DATA_TYPE_UBIGINT;
  tags[12].buffer_length = sizeof(id.u8);
  tags[12].buffer = &id.u8;
  tags[12].length = &tags[12].buffer_length;
  tags[12].is_null = NULL;
  // insert 10 records
  struct {
    int64_t  ts[10];
    int8_t   b[10];
    int8_t   v1[10];
    int16_t  v2[10];
    int32_t  v4[10];
    int64_t  v8[10];
    float    f4[10];
    double   f8[10];
    char     bin[10][40];
    char     blob[10][80];
    uint8_t  u1[10];
    uint16_t u2[10];
    uint32_t u4[10];
    uint64_t u8[10];
  } v;

  int32_t* t8_len = malloc(sizeof(int32_t) * 10);
  int32_t* t16_len = malloc(sizeof(int32_t) * 10);
  int32_t* t32_len = malloc(sizeof(int32_t) * 10);
  int32_t* t64_len = malloc(sizeof(int32_t) * 10);
  int32_t* float_len = malloc(sizeof(int32_t) * 10);
  int32_t* double_len = malloc(sizeof(int32_t) * 10);
  int32_t* bin_len = malloc(sizeof(int32_t) * 10);
  int32_t* blob_len = malloc(sizeof(int32_t) * 10);
  int32_t* u8_len = malloc(sizeof(int32_t) * 10);
  int32_t* u16_len = malloc(sizeof(int32_t) * 10);
  int32_t* u32_len = malloc(sizeof(int32_t) * 10);
  int32_t* u64_len = malloc(sizeof(int32_t) * 10);

  TAOS_STMT*      stmt = taos_stmt_init(taos);
  TAOS_MULTI_BIND params[14];
  char            is_null[10] = {0};

  params[0].buffer_type = TSDB_DATA_TYPE_TIMESTAMP;
  params[0].buffer_length = sizeof(v.ts[0]);
  params[0].buffer = v.ts;
  params[0].length = t64_len;
  params[0].is_null = is_null;
  params[0].num = 10;

  params[1].buffer_type = TSDB_DATA_TYPE_BOOL;
  params[1].buffer_length = sizeof(v.b[0]);
  params[1].buffer = v.b;
  params[1].length = t8_len;
  params[1].is_null = is_null;
  params[1].num = 10;

  params[2].buffer_type = TSDB_DATA_TYPE_TINYINT;
  params[2].buffer_length = sizeof(v.v1[0]);
  params[2].buffer = v.v1;
  params[2].length = t8_len;
  params[2].is_null = is_null;
  params[2].num = 10;

  params[3].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  params[3].buffer_length = sizeof(v.v2[0]);
  params[3].buffer = v.v2;
  params[3].length = t16_len;
  params[3].is_null = is_null;
  params[3].num = 10;

  params[4].buffer_type = TSDB_DATA_TYPE_INT;
  params[4].buffer_length = sizeof(v.v4[0]);
  params[4].buffer = v.v4;
  params[4].length = t32_len;
  params[4].is_null = is_null;
  params[4].num = 10;

  params[5].buffer_type = TSDB_DATA_TYPE_BIGINT;
  params[5].buffer_length = sizeof(v.v8[0]);
  params[5].buffer = v.v8;
  params[5].length = t64_len;
  params[5].is_null = is_null;
  params[5].num = 10;

  params[6].buffer_type = TSDB_DATA_TYPE_FLOAT;
  params[6].buffer_length = sizeof(v.f4[0]);
  params[6].buffer = v.f4;
  params[6].length = float_len;
  params[6].is_null = is_null;
  params[6].num = 10;

  params[7].buffer_type = TSDB_DATA_TYPE_DOUBLE;
  params[7].buffer_length = sizeof(v.f8[0]);
  params[7].buffer = v.f8;
  params[7].length = double_len;
  params[7].is_null = is_null;
  params[7].num = 10;

  params[8].buffer_type = TSDB_DATA_TYPE_BINARY;
  params[8].buffer_length = sizeof(v.bin[0]);
  params[8].buffer = v.bin;
  params[8].length = bin_len;
  params[8].is_null = is_null;
  params[8].num = 10;

  params[9].buffer_type = TSDB_DATA_TYPE_NCHAR;
  params[9].buffer_length = sizeof(v.blob[0]);
  params[9].buffer = v.blob;
  params[9].length = blob_len;
  params[9].is_null = is_null;
  params[9].num = 10;

  params[10].buffer_type = TSDB_DATA_TYPE_UTINYINT;
  params[10].buffer_length = sizeof(v.u1[0]);
  params[10].buffer = v.u1;
  params[10].length = u8_len;
  params[10].is_null = is_null;
  params[10].num = 10;

  params[11].buffer_type = TSDB_DATA_TYPE_USMALLINT;
  params[11].buffer_length = sizeof(v.u2[0]);
  params[11].buffer = v.u2;
  params[11].length = u16_len;
  params[11].is_null = is_null;
  params[11].num = 10;

  params[12].buffer_type = TSDB_DATA_TYPE_UINT;
  params[12].buffer_length = sizeof(v.u4[0]);
  params[12].buffer = v.u4;
  params[12].length = u32_len;
  params[12].is_null = is_null;
  params[12].num = 10;

  params[13].buffer_type = TSDB_DATA_TYPE_UBIGINT;
  params[13].buffer_length = sizeof(v.u8[0]);
  params[13].buffer = v.u8;
  params[13].length = u64_len;
  params[13].is_null = is_null;
  params[13].num = 10;

  sql = "insert into ? using st1 tags(?,?,?,?,?,?,?,?,?,?,?,?,?) values(?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
  code = taos_stmt_prepare(stmt, sql, 0);
  if (code != 0) {
    printf("\033[31mfailed to execute taos_stmt_prepare. error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  code = taos_stmt_set_tbname_tags(stmt, "m1", tags);
  if (code != 0) {
    printf("\033[31mfailed to execute taos_stmt_set_tbname_tags. error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  int64_t ts = 1591060628000;
  for (int i = 0; i < 10; ++i) {
    v.ts[i] = ts++;
    is_null[i] = 0;

    v.b[i] = (int8_t)i % 2;
    v.v1[i] = (int8_t)i;
    v.v2[i] = (int16_t)(i * 2);
    v.v4[i] = (int32_t)(i * 4);
    v.v8[i] = (int64_t)(i * 8);
    v.f4[i] = (float)(i * 40);
    v.f8[i] = (double)(i * 80);
    for (int j = 0; j < sizeof(v.bin[0]); ++j) {
      v.bin[i][j] = (char)(i + '0');
    }
    strcpy(v.blob[i], "一二三四五六七八九十");
    v.u1[i] = (uint8_t)i;
    v.u2[i] = (uint16_t)(i * 2);
    v.u4[i] = (uint32_t)(i * 4);
    v.u8[i] = (uint64_t)(i * 8);

    t8_len[i] = sizeof(int8_t);
    t16_len[i] = sizeof(int16_t);
    t32_len[i] = sizeof(int32_t);
    t64_len[i] = sizeof(int64_t);
    float_len[i] = sizeof(float);
    double_len[i] = sizeof(double);
    bin_len[i] = sizeof(v.bin[0]);
    blob_len[i] = (int32_t)strlen(v.blob[i]);
    u8_len[i] = sizeof(uint8_t);
    u16_len[i] = sizeof(uint16_t);
    u32_len[i] = sizeof(uint32_t);
    u64_len[i] = sizeof(uint64_t);
  }

  taos_stmt_bind_param_batch(stmt, params);
  taos_stmt_add_batch(stmt);

  if (taos_stmt_execute(stmt) != 0) {
    printf("\033[31mfailed to execute insert statement.error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }
  
  int affectedRows = taos_stmt_affected_rows(stmt);
  printf("successfully inserted %d rows\n", affectedRows);

  taos_stmt_close(stmt);

  // query the records
  stmt = taos_stmt_init(taos);
  taos_stmt_prepare(stmt, "SELECT * FROM m1 WHERE v1 > ? AND v2 < ?", 0);

  TAOS_BIND qparams[2];

  int8_t  v1 = 5;
  int16_t v2 = 15;
  qparams[0].buffer_type = TSDB_DATA_TYPE_TINYINT;
  qparams[0].buffer_length = sizeof(v1);
  qparams[0].buffer = &v1;
  qparams[0].length = &qparams[0].buffer_length;
  qparams[0].is_null = NULL;

  qparams[1].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  qparams[1].buffer_length = sizeof(v2);
  qparams[1].buffer = &v2;
  qparams[1].length = &qparams[1].buffer_length;
  qparams[1].is_null = NULL;

  taos_stmt_bind_param(stmt, qparams);
  if (taos_stmt_execute(stmt) != 0) {
    printf("\033[31mfailed to execute select statement.error:%s\033[0m\n", taos_stmt_errstr(stmt));
    taos_stmt_close(stmt);
    exit(EXIT_FAILURE);
  }

  result = taos_stmt_use_result(stmt);

  TAOS_ROW    row;
  int         rows = 0;
  int         num_fields = taos_num_fields(result);
  TAOS_FIELD* fields = taos_fetch_fields(result);

  // fetch the records row by row
  while ((row = taos_fetch_row(result))) {
    char temp[256] = {0};
    rows++;
    taos_print_row(temp, row, fields, num_fields);
    printf("%s\n", temp);
  }

  taos_free_result(result);
  taos_stmt_close(stmt);

  free(t8_len);
  free(t16_len);
  free(t32_len);
  free(t64_len);
  free(float_len);
  free(double_len);
  free(bin_len);
  free(blob_len);
  free(u8_len);
  free(u16_len);
  free(u32_len);
  free(u64_len);
  
}

/**
 * @brief Verify the upper/lower case of tableName for create(by setTableName)/query/show/describe/drop.
 *  https://jira.taosdata.com:18080/browse/TS-904
 *  https://jira.taosdata.com:18090/pages/viewpage.action?pageId=129140555
 * @param taos
 */
void verify_prepare4(TAOS* taos) {
  printf("Verify the upper/lower case of tableName for create(by setTableName)/query/show/describe/drop etc.\n");

  TAOS_RES* result = taos_query(taos, "drop database if exists test;");
  taos_free_result(result);
  usleep(100000);
  result = taos_query(taos, "create database test;");

  int code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create database, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }
  taos_free_result(result);

  usleep(100000);
  taos_select_db(taos, "test");

  // create table
  const char* sql =
      "create stable st1 (ts timestamp, b bool, v1 tinyint, v2 smallint, v4 int, v8 bigint, f4 float, f8 double, bin "
      "binary(40), blob nchar(10), u1 tinyint unsigned, u2 smallint unsigned, u4 int unsigned, u8 bigint unsigned) "
      "tags "
      "(b_tag bool, v1_tag tinyint, v2_tag smallint, v4_tag int, v8_tag bigint, f4_tag float, f8_tag double, bin_tag "
      "binary(40), blob_tag nchar(10), u1_tag tinyint unsigned, u2_tag smallint unsigned, u4_tag int unsigned, u8_tag "
      "bigint "
      "unsigned)";
  result = taos_query(taos, sql);
  code = taos_errno(result);
  if (code != 0) {
    printf("\033[31mfailed to create table, reason:%s\033[0m\n", taos_errstr(result));
    taos_free_result(result);
    exit(EXIT_FAILURE);
  }
  taos_free_result(result);

  TAOS_BIND tags[13];

  struct {
    int8_t   b;
    int8_t   v1;
    int16_t  v2;
    int32_t  v4;
    int64_t  v8;
    float    f4;
    double   f8;
    char     bin[40];
    char     blob[80];
    uint8_t  u1;
    uint16_t u2;
    uint32_t u4;
    uint64_t u8;
  } id = {0};

  id.b = (int8_t)1;
  id.v1 = (int8_t)1;
  id.v2 = (int16_t)2;
  id.v4 = (int32_t)4;
  id.v8 = (int64_t)8;
  id.f4 = (float)40;
  id.f8 = (double)80;
  for (int j = 0; j < sizeof(id.bin); ++j) {
    id.bin[j] = (char)('1' + '0');
  }
  strcpy(id.blob, "一二三四五六七八九十");
  id.u1 = (uint8_t)1;
  id.u2 = (uint16_t)2;
  id.u4 = (uint32_t)4;
  id.u8 = (uint64_t)8;

  tags[0].buffer_type = TSDB_DATA_TYPE_BOOL;
  tags[0].buffer_length = sizeof(id.b);
  tags[0].buffer = &id.b;
  tags[0].length = &tags[0].buffer_length;
  tags[0].is_null = NULL;

  tags[1].buffer_type = TSDB_DATA_TYPE_TINYINT;
  tags[1].buffer_length = sizeof(id.v1);
  tags[1].buffer = &id.v1;
  tags[1].length = &tags[1].buffer_length;
  tags[1].is_null = NULL;

  tags[2].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  tags[2].buffer_length = sizeof(id.v2);
  tags[2].buffer = &id.v2;
  tags[2].length = &tags[2].buffer_length;
  tags[2].is_null = NULL;

  tags[3].buffer_type = TSDB_DATA_TYPE_INT;
  tags[3].buffer_length = sizeof(id.v4);
  tags[3].buffer = &id.v4;
  tags[3].length = &tags[3].buffer_length;
  tags[3].is_null = NULL;

  tags[4].buffer_type = TSDB_DATA_TYPE_BIGINT;
  tags[4].buffer_length = sizeof(id.v8);
  tags[4].buffer = &id.v8;
  tags[4].length = &tags[4].buffer_length;
  tags[4].is_null = NULL;

  tags[5].buffer_type = TSDB_DATA_TYPE_FLOAT;
  tags[5].buffer_length = sizeof(id.f4);
  tags[5].buffer = &id.f4;
  tags[5].length = &tags[5].buffer_length;
  tags[5].is_null = NULL;

  tags[6].buffer_type = TSDB_DATA_TYPE_DOUBLE;
  tags[6].buffer_length = sizeof(id.f8);
  tags[6].buffer = &id.f8;
  tags[6].length = &tags[6].buffer_length;
  tags[6].is_null = NULL;

  tags[7].buffer_type = TSDB_DATA_TYPE_BINARY;
  tags[7].buffer_length = sizeof(id.bin);
  tags[7].buffer = &id.bin;
  tags[7].length = &tags[7].buffer_length;
  tags[7].is_null = NULL;

  tags[8].buffer_type = TSDB_DATA_TYPE_NCHAR;
  tags[8].buffer_length = strlen(id.blob);
  tags[8].buffer = &id.blob;
  tags[8].length = &tags[8].buffer_length;
  tags[8].is_null = NULL;

  tags[9].buffer_type = TSDB_DATA_TYPE_UTINYINT;
  tags[9].buffer_length = sizeof(id.u1);
  tags[9].buffer = &id.u1;
  tags[9].length = &tags[9].buffer_length;
  tags[9].is_null = NULL;

  tags[10].buffer_type = TSDB_DATA_TYPE_USMALLINT;
  tags[10].buffer_length = sizeof(id.u2);
  tags[10].buffer = &id.u2;
  tags[10].length = &tags[10].buffer_length;
  tags[10].is_null = NULL;

  tags[11].buffer_type = TSDB_DATA_TYPE_UINT;
  tags[11].buffer_length = sizeof(id.u4);
  tags[11].buffer = &id.u4;
  tags[11].length = &tags[11].buffer_length;
  tags[11].is_null = NULL;

  tags[12].buffer_type = TSDB_DATA_TYPE_UBIGINT;
  tags[12].buffer_length = sizeof(id.u8);
  tags[12].buffer = &id.u8;
  tags[12].length = &tags[12].buffer_length;
  tags[12].is_null = NULL;
  // insert 10 records
  struct {
    int64_t  ts[10];
    int8_t   b[10];
    int8_t   v1[10];
    int16_t  v2[10];
    int32_t  v4[10];
    int64_t  v8[10];
    float    f4[10];
    double   f8[10];
    char     bin[10][40];
    char     blob[10][80];
    uint8_t  u1[10];
    uint16_t u2[10];
    uint32_t u4[10];
    uint64_t u8[10];
  } v;

  int32_t* t8_len = malloc(sizeof(int32_t) * 10);
  int32_t* t16_len = malloc(sizeof(int32_t) * 10);
  int32_t* t32_len = malloc(sizeof(int32_t) * 10);
  int32_t* t64_len = malloc(sizeof(int32_t) * 10);
  int32_t* float_len = malloc(sizeof(int32_t) * 10);
  int32_t* double_len = malloc(sizeof(int32_t) * 10);
  int32_t* bin_len = malloc(sizeof(int32_t) * 10);
  int32_t* blob_len = malloc(sizeof(int32_t) * 10);
  int32_t* u8_len = malloc(sizeof(int32_t) * 10);
  int32_t* u16_len = malloc(sizeof(int32_t) * 10);
  int32_t* u32_len = malloc(sizeof(int32_t) * 10);
  int32_t* u64_len = malloc(sizeof(int32_t) * 10);

  TAOS_MULTI_BIND params[14];
  char            is_null[10] = {0};
  params[0].buffer_type = TSDB_DATA_TYPE_TIMESTAMP;
  params[0].buffer_length = sizeof(v.ts[0]);
  params[0].buffer = v.ts;
  params[0].length = t64_len;
  params[0].is_null = is_null;
  params[0].num = 10;

  params[1].buffer_type = TSDB_DATA_TYPE_BOOL;
  params[1].buffer_length = sizeof(v.b[0]);
  params[1].buffer = v.b;
  params[1].length = t8_len;
  params[1].is_null = is_null;
  params[1].num = 10;

  params[2].buffer_type = TSDB_DATA_TYPE_TINYINT;
  params[2].buffer_length = sizeof(v.v1[0]);
  params[2].buffer = v.v1;
  params[2].length = t8_len;
  params[2].is_null = is_null;
  params[2].num = 10;

  params[3].buffer_type = TSDB_DATA_TYPE_SMALLINT;
  params[3].buffer_length = sizeof(v.v2[0]);
  params[3].buffer = v.v2;
  params[3].length = t16_len;
  params[3].is_null = is_null;
  params[3].num = 10;

  params[4].buffer_type = TSDB_DATA_TYPE_INT;
  params[4].buffer_length = sizeof(v.v4[0]);
  params[4].buffer = v.v4;
  params[4].length = t32_len;
  params[4].is_null = is_null;
  params[4].num = 10;

  params[5].buffer_type = TSDB_DATA_TYPE_BIGINT;
  params[5].buffer_length = sizeof(v.v8[0]);
  params[5].buffer = v.v8;
  params[5].length = t64_len;
  params[5].is_null = is_null;
  params[5].num = 10;

  params[6].buffer_type = TSDB_DATA_TYPE_FLOAT;
  params[6].buffer_length = sizeof(v.f4[0]);
  params[6].buffer = v.f4;
  params[6].length = float_len;
  params[6].is_null = is_null;
  params[6].num = 10;

  params[7].buffer_type = TSDB_DATA_TYPE_DOUBLE;
  params[7].buffer_length = sizeof(v.f8[0]);
  params[7].buffer = v.f8;
  params[7].length = double_len;
  params[7].is_null = is_null;
  params[7].num = 10;

  params[8].buffer_type = TSDB_DATA_TYPE_BINARY;
  params[8].buffer_length = sizeof(v.bin[0]);
  params[8].buffer = v.bin;
  params[8].length = bin_len;
  params[8].is_null = is_null;
  params[8].num = 10;

  params[9].buffer_type = TSDB_DATA_TYPE_NCHAR;
  params[9].buffer_length = sizeof(v.blob[0]);
  params[9].buffer = v.blob;
  params[9].length = blob_len;
  params[9].is_null = is_null;
  params[9].num = 10;

  params[10].buffer_type = TSDB_DATA_TYPE_UTINYINT;
  params[10].buffer_length = sizeof(v.u1[0]);
  params[10].buffer = v.u1;
  params[10].length = u8_len;
  params[10].is_null = is_null;
  params[10].num = 10;

  params[11].buffer_type = TSDB_DATA_TYPE_USMALLINT;
  params[11].buffer_length = sizeof(v.u2[0]);
  params[11].buffer = v.u2;
  params[11].length = u16_len;
  params[11].is_null = is_null;
  params[11].num = 10;

  params[12].buffer_type = TSDB_DATA_TYPE_UINT;
  params[12].buffer_length = sizeof(v.u4[0]);
  params[12].buffer = v.u4;
  params[12].length = u32_len;
  params[12].is_null = is_null;
  params[12].num = 10;

  params[13].buffer_type = TSDB_DATA_TYPE_UBIGINT;
  params[13].buffer_length = sizeof(v.u8[0]);
  params[13].buffer = v.u8;
  params[13].length = u64_len;
  params[13].is_null = is_null;
  params[13].num = 10;

// verify table names for upper/lower case
#define VERIFY_CNT 5

  typedef struct {
    char setTbName[20];
    char showName[20];
    char describeName[20];
    char queryName[20];
    char dropName[20];
  } STbNames;

  /**
   * @brief
   *  0       - success expected
   *  NonZero - fail expected
   */
  typedef struct {
    int32_t setTbName;
    int32_t showName;
    int32_t describeName;
    int32_t queryName;
    int32_t dropName;
  } STbNamesResult;

  STbNames       tbName[VERIFY_CNT] = {0};
  STbNamesResult tbNameResult[VERIFY_CNT] = {0};

  STbNames*       pTbName = NULL;
  STbNamesResult* pTbNameResult = NULL;

  pTbName = &tbName[0];
  pTbNameResult = &tbNameResult[0];
  strcpy(pTbName->setTbName, "Mn1");
  strcpy(pTbName->showName, "mn1");
  strcpy(pTbName->describeName, "mn1");
  strcpy(pTbName->queryName, "mn1");
  strcpy(pTbName->dropName, "mn1");

  pTbName = &tbName[1];
  pTbNameResult = &tbNameResult[1];
  strcpy(pTbName->setTbName, "'Mn1'");
  strcpy(pTbName->showName, "'mn1'");
  strcpy(pTbName->describeName, "'mn1'");
  strcpy(pTbName->queryName, "'mn1'");
  strcpy(pTbName->dropName, "'mn1'");

  pTbName = &tbName[2];
  pTbNameResult = &tbNameResult[2];
  strcpy(pTbName->setTbName, "\"Mn1\"");
  strcpy(pTbName->showName, "\"mn1\"");
  strcpy(pTbName->describeName, "\"mn1\"");
  strcpy(pTbName->queryName, "\"mn1\"");
  strcpy(pTbName->dropName, "\"mn1\"");

  pTbName = &tbName[3];
  pTbNameResult = &tbNameResult[3];
  strcpy(pTbName->setTbName, "\"Mn1\"");
  strcpy(pTbName->showName, "'mn1'");
  strcpy(pTbName->describeName, "'mn1'");
  strcpy(pTbName->queryName, "mn1");
  strcpy(pTbName->dropName, "\"mn1\"");

  pTbName = &tbName[4];
  pTbNameResult = &tbNameResult[4];
  strcpy(pTbName->setTbName, "`Mn1`");
  strcpy(pTbName->showName, "Mn1");  // TODO support uniform of ``
  strcpy(pTbName->describeName, "`Mn1`");
  strcpy(pTbName->queryName, "`Mn1`");
  strcpy(pTbName->dropName, "`Mn1`");

  TAOS_STMT* stmt = NULL;

  for (int n = 0; n < VERIFY_CNT; ++n) {
    printf("\033[31m[%d] ===================================\033[0m\n", n);
    pTbName = &tbName[n];
    pTbNameResult = &tbNameResult[n];
    char tmpStr[256] = {0};

    // set table name
    stmt = taos_stmt_init(taos);
    if (!stmt) {
      printf("\033[31m[%d] failed to execute taos_stmt_init. error:%s\033[0m\n", n);
      exit(EXIT_FAILURE);
    }

    sql = "insert into ? using st1 tags(?,?,?,?,?,?,?,?,?,?,?,?,?) values(?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
    code = taos_stmt_prepare(stmt, sql, 0);
    if (code != 0) {
      printf("\033[31mfailed to execute taos_stmt_prepare. error:%s\033[0m\n", taos_stmt_errstr(stmt));
      taos_stmt_close(stmt);
      exit(EXIT_FAILURE);
    }

    printf("[%d] taos_stmt_set_tbname_tags, tbname=%s\n", n, pTbName->setTbName);
    code = taos_stmt_set_tbname_tags(stmt, pTbName->setTbName, tags);
    if ((!pTbNameResult->setTbName && (0 != code)) || (pTbNameResult->setTbName && (0 == code))) {
      printf("\033[31m[%d] failed to execute taos_stmt_set_tbname_tags. error:%s\033[0m\n", n, taos_stmt_errstr(stmt));
      taos_stmt_close(stmt);
      exit(EXIT_FAILURE);
    }

    if (code == 0) {
      int64_t ts = 1591060628000 + 1000 * n;
      for (int i = 0; i < 10; ++i) {
        v.ts[i] = ts++;
        is_null[i] = 0;

        v.b[i] = (int8_t)i % 2;
        v.v1[i] = (int8_t)i;
        v.v2[i] = (int16_t)(i * 2);
        v.v4[i] = (int32_t)(i * 4);
        v.v8[i] = (int64_t)(i * 8);
        v.f4[i] = (float)(i * 40);
        v.f8[i] = (double)(i * 80);
        for (int j = 0; j < sizeof(v.bin[0]); ++j) {
          v.bin[i][j] = (char)(i + '0');
        }
        strcpy(v.blob[i], "一二三四五六七八九十");
        v.u1[i] = (uint8_t)i;
        v.u2[i] = (uint16_t)(i * 2);
        v.u4[i] = (uint32_t)(i * 4);
        v.u8[i] = (uint64_t)(i * 8);

        t8_len[i] = sizeof(int8_t);
        t16_len[i] = sizeof(int16_t);
        t32_len[i] = sizeof(int32_t);
        t64_len[i] = sizeof(int64_t);
        float_len[i] = sizeof(float);
        double_len[i] = sizeof(double);
        bin_len[i] = sizeof(v.bin[0]);
        blob_len[i] = (int32_t)strlen(v.blob[i]);
        u8_len[i] = sizeof(uint8_t);
        u16_len[i] = sizeof(uint16_t);
        u32_len[i] = sizeof(uint32_t);
        u64_len[i] = sizeof(uint64_t);
      }

      taos_stmt_bind_param_batch(stmt, params);
      taos_stmt_add_batch(stmt);

      if (taos_stmt_execute(stmt) != 0) {
        printf("\033[31m[%d] failed to execute insert statement.error:%s\033[0m\n", n, taos_stmt_errstr(stmt));
        taos_stmt_close(stmt);
        exit(EXIT_FAILURE);
      }
    }
    taos_stmt_close(stmt);

    // show the table
    printf("[%d] show tables, tbName = %s\n", n, pTbName->showName);
    stmt = taos_stmt_init(taos);
    sprintf(tmpStr, "show tables like %s", pTbName->showName);
    taos_stmt_prepare(stmt, tmpStr, 0);
    code = taos_stmt_execute(stmt);
    if ((!pTbNameResult->showName && (0 != code)) || (pTbNameResult->showName && (0 == code))) {
      printf("\033[31m[%d] failed to execute show tables like. error:%s\033[0m\n", n, taos_stmt_errstr(stmt));
      taos_stmt_close(stmt);
      exit(EXIT_FAILURE);
    }
    taos_stmt_close(stmt);

    // describe the table
    printf("[%d] describe tables, tbName = %s\n", n, pTbName->describeName);
    stmt = taos_stmt_init(taos);
    sprintf(tmpStr, "describe %s", pTbName->describeName);
    taos_stmt_prepare(stmt, tmpStr, 0);
    code = taos_stmt_execute(stmt);
    if ((!pTbNameResult->describeName && (0 != code)) || (pTbNameResult->describeName && (0 == code))) {
      printf("\033[31m[%d] failed to execute describe tables. error:%s\033[0m\n", n, taos_stmt_errstr(stmt));
      taos_stmt_close(stmt);
      exit(EXIT_FAILURE);
    }
    taos_stmt_close(stmt);

    // query the records
    printf("[%d] select statement, tbName = %s\n", n, pTbName->queryName);
    stmt = taos_stmt_init(taos);
    sprintf(tmpStr, "SELECT * FROM %s", pTbName->queryName);
    taos_stmt_prepare(stmt, tmpStr, 0);

    TAOS_BIND qparams[2];

    int8_t  v1 = 5;
    int16_t v2 = 15;
    qparams[0].buffer_type = TSDB_DATA_TYPE_TINYINT;
    qparams[0].buffer_length = sizeof(v1);
    qparams[0].buffer = &v1;
    qparams[0].length = &qparams[0].buffer_length;
    qparams[0].is_null = NULL;

    qparams[1].buffer_type = TSDB_DATA_TYPE_SMALLINT;
    qparams[1].buffer_length = sizeof(v2);
    qparams[1].buffer = &v2;
    qparams[1].length = &qparams[1].buffer_length;
    qparams[1].is_null = NULL;

    taos_stmt_bind_param(stmt, qparams);

    code = taos_stmt_execute(stmt);
    if ((!pTbNameResult->queryName && (0 != code)) || (pTbNameResult->queryName && (0 == code))) {
      printf("\033[31m[%d] failed to execute select statement.error:%s\033[0m\n", n, taos_stmt_errstr(stmt));
      taos_stmt_close(stmt);
      exit(EXIT_FAILURE);
    }

    result = taos_stmt_use_result(stmt);

    TAOS_ROW    row;
    int         rows = 0;
    int         num_fields = taos_num_fields(result);
    TAOS_FIELD* fields = taos_fetch_fields(result);

    // fetch the records row by row
    while ((row = taos_fetch_row(result))) {
      char temp[256] = {0};
      rows++;
      taos_print_row(temp, row, fields, num_fields);
      printf("[%d] row = %s\n", n, temp);
    }

    taos_free_result(result);
    taos_stmt_close(stmt);

    // drop table
    printf("[%d] drop table, tbName = %s\n", n, pTbName->dropName);
    stmt = taos_stmt_init(taos);
    sprintf(tmpStr, "drop table %s", pTbName->dropName);
    taos_stmt_prepare(stmt, tmpStr, 0);
    code = taos_stmt_execute(stmt);
    if ((!pTbNameResult->dropName && (0 != code)) || (pTbNameResult->dropName && (0 == code))) {
      printf("\033[31m[%d] failed to drop table. error:%s\033[0m\n", n, taos_stmt_errstr(stmt));
      taos_stmt_close(stmt);
      exit(EXIT_FAILURE);
    }
    taos_stmt_close(stmt);
  }

  free(t8_len);
  free(t16_len);
  free(t32_len);
  free(t64_len);
  free(float_len);
  free(double_len);
  free(bin_len);
  free(blob_len);
  free(u8_len);
  free(u16_len);
  free(u32_len);
  free(u64_len);
}

int main(int argc, char* argv[]) {
  const char* host = "127.0.0.1";
  const char* user = "root";
  const char* passwd = "taosdata";

  taos_options(TSDB_OPTION_TIMEZONE, "GMT-8");
  TAOS* taos = taos_connect(host, user, passwd, "", 0);
  if (taos == NULL) {
    printf("\033[31mfailed to connect to db, reason:%s\033[0m\n", taos_errstr(taos));
    exit(1);
  }

  char* info = taos_get_server_info(taos);
  printf("server info: %s\n", info);
  info = taos_get_client_info(taos);
  printf("client info: %s\n", info);
  printf("************  verify prepare  *************\n");
  verify_prepare(taos);
  printf("************  verify prepare2  *************\n");
  verify_prepare2(taos);
  printf("************  verify prepare3  *************\n");
  verify_prepare3(taos);
  printf("************  verify prepare4  *************\n");
  verify_prepare4(taos);
  printf("************  verify end  *************\n");
  exit(EXIT_SUCCESS);
}

查看源码

无模式写入示例

无模式写入

#include "os.h"
#include "taos.h"
#include "taoserror.h"

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>

bool verbose = false;


void printThreadId(pthread_t id, char* buf)
{
  size_t i;
  for (i = sizeof(i); i; --i)
    sprintf(buf + strlen(buf), "%02x", *(((unsigned char*) &id) + i - 1));
}

static int64_t getTimeInUs() {
  struct timeval systemTime;
  gettimeofday(&systemTime, NULL);
  return (int64_t)systemTime.tv_sec * 1000000L + (int64_t)systemTime.tv_usec;
}

typedef struct {
  char** lines;
  int numLines;
} SThreadLinesBatch;

typedef struct  {
  TAOS* taos;
  int protocol;
  int numBatches;
  SThreadLinesBatch *batches;
  int64_t costTime;
} SThreadInsertArgs;

static void* insertLines(void* args) {
  SThreadInsertArgs* insertArgs = (SThreadInsertArgs*) args;
  char tidBuf[32] = {0};
  printThreadId(pthread_self(), tidBuf);
  for (int i = 0; i < insertArgs->numBatches; ++i) {
    SThreadLinesBatch* batch = insertArgs->batches + i;
    if (verbose) printf("%s, thread: 0x%s\n", "begin taos_insert_lines", tidBuf);
    int64_t begin = getTimeInUs();
    //int32_t code = taos_insert_lines(insertArgs->taos, batch->lines, batch->numLines);
    TAOS_RES * res = taos_schemaless_insert(insertArgs->taos, batch->lines, batch->numLines, insertArgs->protocol, TSDB_SML_TIMESTAMP_MILLI_SECONDS);
    int32_t code = taos_errno(res);
    int64_t end = getTimeInUs();
    insertArgs->costTime += end - begin;
    if (verbose) printf("code: %d, %s. time used:%"PRId64", thread: 0x%s\n", code, tstrerror(code), end - begin, tidBuf);
  }
  return NULL;
}

int32_t getTelenetTemplate(char* lineTemplate, int templateLen) {
  char* sample = "sta%d %lld 44.3 t0=False t1=127i8 t2=32 t3=%di32 t4=9223372036854775807i64 t5=11.12345f32 t6=22.123456789f64 t7=\"hpxzrdiw\" t8=\"ncharTagValue\" t9=127i8";
  snprintf(lineTemplate, templateLen, "%s", sample);
  return 0;
}

int32_t getLineTemplate(char* lineTemplate, int templateLen, int numFields) {
  if (numFields <= 4) {
    char* sample = "sta%d,t3=%di32 c3=2147483647i32,c4=9223372036854775807i64,c9=11.12345f32,c10=22.123456789f64 %lld";
    snprintf(lineTemplate, templateLen, "%s", sample);
    return 0;
  }

  if (numFields <= 13) {
     char* sample = "sta%d,t0=true,t1=127i8,t2=32767i16,t3=%di32,t4=9223372036854775807i64,t9=11.12345f32,t10=22.123456789f64,t11=\"binaryTagValue\",t12=L\"ncharTagValue\" c0=true,c1=127i8,c2=32767i16,c3=2147483647i32,c4=9223372036854775807i64,c5=254u8,c6=32770u16,c7=2147483699u32,c8=9223372036854775899u64,c9=11.12345f32,c10=22.123456789f64,c11=\"binaryValue\",c12=L\"ncharValue\" %lld";
     snprintf(lineTemplate, templateLen, "%s", sample);
     return 0;
  }

  char* lineFormatTable = "sta%d,t0=true,t1=127i8,t2=32767i16,t3=%di32 ";
  snprintf(lineTemplate+strlen(lineTemplate), templateLen-strlen(lineTemplate), "%s", lineFormatTable);

  int offset[] = {numFields*2/5, numFields*4/5, numFields};

  for (int i = 0; i < offset[0]; ++i) {
    snprintf(lineTemplate+strlen(lineTemplate), templateLen-strlen(lineTemplate), "c%d=%di32,", i, i);
  }

  for (int i=offset[0]+1; i < offset[1]; ++i) {
    snprintf(lineTemplate+strlen(lineTemplate), templateLen-strlen(lineTemplate), "c%d=%d.43f64,", i, i);
  }

  for (int i = offset[1]+1; i < offset[2]; ++i) {
    snprintf(lineTemplate+strlen(lineTemplate), templateLen-strlen(lineTemplate), "c%d=\"%d\",", i, i);
  }
  char* lineFormatTs = " %lld";
  snprintf(lineTemplate+strlen(lineTemplate)-1, templateLen-strlen(lineTemplate)+1, "%s", lineFormatTs);

  return 0;
}

int32_t generateLine(char* line, int lineLen, char* lineTemplate, int protocol, int superTable, int childTable, int64_t ts) {
  if (protocol == TSDB_SML_LINE_PROTOCOL) {
    snprintf(line, lineLen, lineTemplate, superTable, childTable, ts);               
  } else if (protocol == TSDB_SML_TELNET_PROTOCOL) {
    snprintf(line, lineLen, lineTemplate, superTable, ts, childTable);
  }
  return TSDB_CODE_SUCCESS;
}

int32_t setupSuperTables(TAOS* taos, char* lineTemplate, int protocol,
                         int numSuperTables, int numChildTables, int numRowsPerChildTable,
                         int maxBatchesPerThread, int64_t ts) {
  printf("setup supertables...");
  {
    char** linesStb = calloc(numSuperTables, sizeof(char*));
    for (int i = 0; i < numSuperTables; i++) {
      char* lineStb = calloc(strlen(lineTemplate)+128, 1);
      generateLine(lineStb, strlen(lineTemplate)+128, lineTemplate, protocol, i,
                   numSuperTables * numChildTables,
                   ts + numSuperTables * numChildTables * numRowsPerChildTable);
      linesStb[i] = lineStb;
    }
    SThreadInsertArgs args = {0};
    args.protocol = protocol;
    args.batches = calloc(maxBatchesPerThread, sizeof(maxBatchesPerThread));
    args.taos = taos;
    args.batches[0].lines = linesStb;
    args.batches[0].numLines = numSuperTables;
    insertLines(&args);
    free(args.batches);
    for (int i = 0; i < numSuperTables; ++i) {
      free(linesStb[i]);
    }
    free(linesStb);
  }
  return TSDB_CODE_SUCCESS;
}

int main(int argc, char* argv[]) {
  int numThreads = 8;
  int maxBatchesPerThread = 1024;	

  int numSuperTables = 1;
  int numChildTables = 256;
  int numRowsPerChildTable = 8192;
  int numFields = 13;

  int maxLinesPerBatch = 16384;

  int protocol = TSDB_SML_TELNET_PROTOCOL;
  int assembleSTables = 0;

  int opt;
  while ((opt = getopt(argc, argv, "s:c:r:f:t:b:p:w:hv")) != -1) {
    switch (opt) {
      case 's':
        numSuperTables = atoi(optarg);
        break;
      case 'c':
        numChildTables = atoi(optarg);
        break;
      case 'r':
        numRowsPerChildTable = atoi(optarg);
        break;
      case 'f':
        numFields = atoi(optarg);
        break;
      case 't':
        numThreads = atoi(optarg);
        break;
      case 'b':
        maxLinesPerBatch = atoi(optarg);
        break;
      case 'v':
        verbose = true;
        break;
      case 'a':
        assembleSTables = atoi(optarg);
        break;
      case 'p':
        if (optarg[0] == 't') {
          protocol = TSDB_SML_TELNET_PROTOCOL;
        } else if (optarg[0] == 'l') {
          protocol = TSDB_SML_LINE_PROTOCOL;
        } else if (optarg[0] == 'j') {
          protocol = TSDB_SML_JSON_PROTOCOL;
        }
        break;
      case 'h':
        fprintf(stderr, "Usage: %s -s supertable -c childtable -r rows -f fields -t threads -b maxlines_per_batch -p [t|l|j] -a assemble-stables -v\n",
                argv[0]);
        exit(0);
      default: /* '?' */
        fprintf(stderr, "Usage: %s -s supertable -c childtable -r rows -f fields -t threads -b maxlines_per_batch -p [t|l|j] -a assemble-stables -v\n",
                argv[0]);
        exit(-1);
    }
  }

  TAOS_RES*   result;
  //const char* host = "127.0.0.1";
  const char* host = NULL;
  const char* user = "root";
  const char* passwd = "taosdata";

  taos_options(TSDB_OPTION_TIMEZONE, "GMT-8");
  TAOS* taos = taos_connect(host, user, passwd, "", 0);
  if (taos == NULL) {
    printf("\033[31mfailed to connect to db, reason:%s\033[0m\n", taos_errstr(taos));
    exit(1);
  }

  maxBatchesPerThread = (numSuperTables*numChildTables*numRowsPerChildTable)/(numThreads * maxLinesPerBatch) + 1;

  char* info = taos_get_server_info(taos);
  printf("server info: %s\n", info);
  info = taos_get_client_info(taos);
  printf("client info: %s\n", info);
  result = taos_query(taos, "drop database if exists db;");
  taos_free_result(result);
  usleep(100000);
  result = taos_query(taos, "create database db precision 'us';");
  taos_free_result(result);
  usleep(100000);

  (void)taos_select_db(taos, "db");

  time_t  ct = time(0);
  int64_t ts = ct * 1000 ;

  char* lineTemplate = calloc(65536, sizeof(char));
  if (protocol == TSDB_SML_LINE_PROTOCOL) {
    getLineTemplate(lineTemplate, 65535, numFields);
  } else if (protocol == TSDB_SML_TELNET_PROTOCOL ) {
    getTelenetTemplate(lineTemplate, 65535);
  }

  if (assembleSTables) {
    setupSuperTables(taos, lineTemplate, protocol,
                     numSuperTables, numChildTables, numRowsPerChildTable, maxBatchesPerThread, ts);
  }

  printf("generate lines...\n");
  pthread_t* tids = calloc(numThreads, sizeof(pthread_t));
  SThreadInsertArgs* argsThread = calloc(numThreads, sizeof(SThreadInsertArgs));
  for (int i = 0; i < numThreads; ++i) {
    argsThread[i].batches = calloc(maxBatchesPerThread, sizeof(SThreadLinesBatch));	  
    argsThread[i].taos = taos;
    argsThread[i].numBatches = 0;
    argsThread[i].protocol = protocol;
  }

  int64_t totalLines = numSuperTables * numChildTables * numRowsPerChildTable;
  int totalBatches = (int) ((totalLines) / maxLinesPerBatch);
  if (totalLines % maxLinesPerBatch != 0) {
    totalBatches += 1;
  }

  char*** allBatches = calloc(totalBatches, sizeof(char**));
  for (int i = 0; i < totalBatches; ++i) {
    allBatches[i] = calloc(maxLinesPerBatch, sizeof(char*));
    int threadNo = i % numThreads;
    int batchNo = i / numThreads;
    argsThread[threadNo].batches[batchNo].lines = allBatches[i];
    argsThread[threadNo].numBatches = batchNo + 1;
  }

  int l = 0;
  for (int i = 0; i < numSuperTables; ++i) {
    for (int j = 0; j < numChildTables; ++j) {
      for (int k = 0; k < numRowsPerChildTable; ++k) {
        int stIdx = i;
        int ctIdx = numSuperTables*numChildTables + j;
        char* line = calloc(strlen(lineTemplate)+128, 1);
        generateLine(line, strlen(lineTemplate)+128, lineTemplate, protocol, stIdx, ctIdx, ts + l);
        int batchNo = l / maxLinesPerBatch;
        int lineNo = l % maxLinesPerBatch;
        allBatches[batchNo][lineNo] =  line;
        argsThread[batchNo % numThreads].batches[batchNo/numThreads].numLines = lineNo + 1;
        ++l;
      }
    }
  }

  printf("begin multi-thread insertion...\n");
  int64_t begin = taosGetTimestampUs();

  for (int i=0; i < numThreads; ++i) {
    pthread_create(tids+i, NULL, insertLines, argsThread+i);
  }
  for (int i = 0; i < numThreads; ++i) {
    pthread_join(tids[i], NULL);
  }
  int64_t end = taosGetTimestampUs();

  size_t linesNum = numSuperTables*numChildTables*numRowsPerChildTable;
  printf("TOTAL LINES: %zu\n", linesNum);
  printf("THREADS: %d\n", numThreads);
  printf("TIME: %d(ms)\n", (int)(end-begin)/1000);
  double throughput = (double)(totalLines)/(double)(end-begin) * 1000000;
  printf("THROUGHPUT:%d/s\n", (int)throughput);

  for (int i = 0; i < totalBatches; ++i) {
    free(allBatches[i]);
  }
  free(allBatches);

  for (int i = 0; i < numThreads; i++) {
    free(argsThread[i].batches);
  }    
  free(argsThread);
  free(tids);

  free(lineTemplate);
  taos_close(taos);
  return 0;
}

查看源码

订阅和消费示例

订阅和消费

// sample code for TDengine subscribe/consume API
// to compile: gcc -o subscribe subscribe.c -ltaos

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <taos.h>  // include TDengine header file
#include <unistd.h>

int nTotalRows;

void print_result(TAOS_RES* res, int blockFetch) {
  TAOS_ROW    row = NULL;
  int         num_fields = taos_num_fields(res);
  TAOS_FIELD* fields = taos_fetch_fields(res);
  int         nRows = 0;

  if (blockFetch) {
    nRows = taos_fetch_block(res, &row);
    // for (int i = 0; i < nRows; i++) {
    //  taos_print_row(buf, row + i, fields, num_fields);
    //  puts(buf);
    //}
  } else {
    while ((row = taos_fetch_row(res))) {
      char buf[4096] = {0};
      taos_print_row(buf, row, fields, num_fields);
      puts(buf);
      nRows++;
    }
  }

  nTotalRows += nRows;
  printf("%d rows consumed.\n", nRows);
}

void subscribe_callback(TAOS_SUB* tsub, TAOS_RES* res, void* param, int code) { print_result(res, *(int*)param); }

void check_row_count(int line, TAOS_RES* res, int expected) {
  int      actual = 0;
  TAOS_ROW row;
  while ((row = taos_fetch_row(res))) {
    actual++;
  }
  if (actual != expected) {
    printf("line %d: row count mismatch, expected: %d, actual: %d\n", line, expected, actual);
  } else {
    printf("line %d: %d rows consumed as expected\n", line, actual);
  }
}

void do_query(TAOS* taos, const char* sql) {
  TAOS_RES* res = taos_query(taos, sql);
  taos_free_result(res);
}

void run_test(TAOS* taos) {
  do_query(taos, "drop database if exists test;");

  usleep(100000);
  do_query(taos, "create database test;");
  usleep(100000);
  do_query(taos, "use test;");

  usleep(100000);
  do_query(taos, "create table meters(ts timestamp, a int) tags(area int);");

  do_query(taos, "create table t0 using meters tags(0);");
  do_query(taos, "create table t1 using meters tags(1);");
  do_query(taos, "create table t2 using meters tags(2);");
  do_query(taos, "create table t3 using meters tags(3);");
  do_query(taos, "create table t4 using meters tags(4);");
  do_query(taos, "create table t5 using meters tags(5);");
  do_query(taos, "create table t6 using meters tags(6);");
  do_query(taos, "create table t7 using meters tags(7);");
  do_query(taos, "create table t8 using meters tags(8);");
  do_query(taos, "create table t9 using meters tags(9);");

  do_query(taos, "insert into t0 values('2020-01-01 00:00:00.000', 0);");
  do_query(taos, "insert into t0 values('2020-01-01 00:01:00.000', 0);");
  do_query(taos, "insert into t0 values('2020-01-01 00:02:00.000', 0);");
  do_query(taos, "insert into t1 values('2020-01-01 00:00:00.000', 0);");
  do_query(taos, "insert into t1 values('2020-01-01 00:01:00.000', 0);");
  do_query(taos, "insert into t1 values('2020-01-01 00:02:00.000', 0);");
  do_query(taos, "insert into t1 values('2020-01-01 00:03:00.000', 0);");
  do_query(taos, "insert into t2 values('2020-01-01 00:00:00.000', 0);");
  do_query(taos, "insert into t2 values('2020-01-01 00:01:00.000', 0);");
  do_query(taos, "insert into t2 values('2020-01-01 00:01:01.000', 0);");
  do_query(taos, "insert into t2 values('2020-01-01 00:01:02.000', 0);");
  do_query(taos, "insert into t3 values('2020-01-01 00:01:02.000', 0);");
  do_query(taos, "insert into t4 values('2020-01-01 00:01:02.000', 0);");
  do_query(taos, "insert into t5 values('2020-01-01 00:01:02.000', 0);");
  do_query(taos, "insert into t6 values('2020-01-01 00:01:02.000', 0);");
  do_query(taos, "insert into t7 values('2020-01-01 00:01:02.000', 0);");
  do_query(taos, "insert into t8 values('2020-01-01 00:01:02.000', 0);");
  do_query(taos, "insert into t9 values('2020-01-01 00:01:02.000', 0);");

  // super tables subscription
  usleep(1000000);

  TAOS_SUB* tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
  TAOS_RES* res = taos_consume(tsub);
  check_row_count(__LINE__, res, 18);

  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 0);

  do_query(taos, "insert into t0 values('2020-01-01 00:02:00.001', 0);");
  do_query(taos, "insert into t8 values('2020-01-01 00:01:03.000', 0);");
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 2);

  do_query(taos, "insert into t2 values('2020-01-01 00:01:02.001', 0);");
  do_query(taos, "insert into t1 values('2020-01-01 00:03:00.001', 0);");
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 2);

  do_query(taos, "insert into t1 values('2020-01-01 00:03:00.002', 0);");
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 1);

  // keep progress information and restart subscription
  taos_unsubscribe(tsub, 1);
  do_query(taos, "insert into t0 values('2020-01-01 00:04:00.000', 0);");
  tsub = taos_subscribe(taos, 1, "test", "select * from meters;", NULL, NULL, 0);
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 24);

  // keep progress information and continue previous subscription
  taos_unsubscribe(tsub, 1);
  tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 0);

  // don't keep progress information and continue previous subscription
  taos_unsubscribe(tsub, 0);
  tsub = taos_subscribe(taos, 0, "test", "select * from meters;", NULL, NULL, 0);
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 24);

  // single meter subscription

  taos_unsubscribe(tsub, 0);
  tsub = taos_subscribe(taos, 0, "test", "select * from t0;", NULL, NULL, 0);
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 5);

  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 0);

  do_query(taos, "insert into t0 values('2020-01-01 00:04:00.001', 0);");
  res = taos_consume(tsub);
  check_row_count(__LINE__, res, 1);

  taos_unsubscribe(tsub, 0);
}

int main(int argc, char* argv[]) {
  const char* host = "127.0.0.1";
  const char* user = "root";
  const char* passwd = "taosdata";
  const char* sql = "select * from meters;";
  const char* topic = "test-multiple";
  int         async = 1, restart = 0, keep = 1, test = 0, blockFetch = 0;

  for (int i = 1; i < argc; i++) {
    if (strncmp(argv[i], "-h=", 3) == 0) {
      host = argv[i] + 3;
      continue;
    }
    if (strncmp(argv[i], "-u=", 3) == 0) {
      user = argv[i] + 3;
      continue;
    }
    if (strncmp(argv[i], "-p=", 3) == 0) {
      passwd = argv[i] + 3;
      continue;
    }
    if (strcmp(argv[i], "-sync") == 0) {
      async = 0;
      continue;
    }
    if (strcmp(argv[i], "-restart") == 0) {
      restart = 1;
      continue;
    }
    if (strcmp(argv[i], "-single") == 0) {
      sql = "select * from t0;";
      topic = "test-single";
      continue;
    }
    if (strcmp(argv[i], "-nokeep") == 0) {
      keep = 0;
      continue;
    }
    if (strncmp(argv[i], "-sql=", 5) == 0) {
      sql = argv[i] + 5;
      topic = "test-custom";
      continue;
    }
    if (strcmp(argv[i], "-test") == 0) {
      test = 1;
      continue;
    }
    if (strcmp(argv[i], "-block-fetch") == 0) {
      blockFetch = 1;
      continue;
    }
  }

  TAOS* taos = taos_connect(host, user, passwd, "", 0);
  if (taos == NULL) {
    printf("failed to connect to db, reason:%s\n", taos_errstr(taos));
    exit(1);
  }

  if (test) {
    run_test(taos);
    taos_close(taos);
    exit(0);
  }

  taos_select_db(taos, "test");
  TAOS_SUB* tsub = NULL;
  if (async) {
    // create an asynchronized subscription, the callback function will be called every 1s
    tsub = taos_subscribe(taos, restart, topic, sql, subscribe_callback, &blockFetch, 1000);
  } else {
    // create an synchronized subscription, need to call 'taos_consume' manually
    tsub = taos_subscribe(taos, restart, topic, sql, NULL, NULL, 0);
  }

  if (tsub == NULL) {
    printf("failed to create subscription.\n");
    exit(0);
  }

  if (async) {
    getchar();
  } else
    while (1) {
      TAOS_RES* res = taos_consume(tsub);
      if (res == NULL) {
        printf("failed to consume data.");
        break;
      } else {
        print_result(res, blockFetch);
        getchar();
      }
    }

  printf("total rows consumed: %d\n", nTotalRows);
  taos_unsubscribe(tsub, keep);
  taos_close(taos);

  return 0;
}

查看源码

info

更多示例代码及下载请见 GitHub。也可以在安装目录下的 examples/c 路径下找到。该目录下有 makefile，在 Linux 环境下，直接执行 make 就可以编译得到执行文件。 **提示：**在 ARM 环境下编译时，请将 makefile 中的 -msse4.2 去掉，这个选项只有在 x64/x86 硬件平台上才能支持。

API 参考

以下分别介绍 TDengine 客户端驱动的基础 API、同步 API、异步 API、订阅 API 和无模式写入 API。

基础 API

基础 API 用于完成创建数据库连接等工作，为其它 API 的执行提供运行时环境。

void taos_init()

初始化运行环境。如果没有主动调用该 API，那么调用 taos_connect() 时驱动将自动调用该 API，故程序一般无需手动调用。
void taos_cleanup()

清理运行环境，应用退出前应调用。
int taos_options(TSDB_OPTION option, const void * arg, ...)

设置客户端选项，目前支持区域设置（TSDB_OPTION_LOCALE）、字符集设置（TSDB_OPTION_CHARSET）、时区设置（TSDB_OPTION_TIMEZONE）、配置文件路径设置（TSDB_OPTION_CONFIGDIR）。区域设置、字符集、时区默认为操作系统当前设置。
char *taos_get_client_info()

获取客户端版本信息。
TAOS *taos_connect(const char *host, const char *user, const char *pass, const char *db, int port)

创建数据库连接，初始化连接上下文。其中需要用户提供的参数包含：
- host：TDengine 集群中任一节点的 FQDN
- user：用户名
- pass：密码
- db：数据库名字，如果用户没有提供，也可以正常连接，用户可以通过该连接创建新的数据库，如果用户提供了数据库名字，则说明该数据库用户已经创建好，缺省使用该数据库
- port：taosd 程序监听的端口
返回值为空表示失败。应用程序需要保存返回的参数，以便后续使用。

info
同一进程可以根据不同的 host/port 连接多个 TDengine 集群
char *taos_get_server_info(TAOS *taos)

获取服务端版本信息。
int taos_select_db(TAOS *taos, const char *db)

将当前的缺省数据库设置为 db。
void taos_close(TAOS *taos)

关闭连接，其中taos是 taos_connect() 返回的句柄。

同步查询 API

本小节介绍 API 均属于同步接口。应用调用后，会阻塞等待响应，直到获得返回结果或错误信息。

TAOS_RES* taos_query(TAOS *taos, const char *sql)

执行 SQL 语句，可以是 DQL、DML 或 DDL 语句。其中的 taos 参数是通过 taos_connect() 获得的句柄。不能通过返回值是否是 NULL 来判断执行结果是否失败，而是需要用 taos_errno() 函数解析结果集中的错误代码来进行判断。
int taos_result_precision(TAOS_RES *res)

返回结果集时间戳字段的精度，0 代表毫秒，1 代表微秒，2 代表纳秒。
TAOS_ROW taos_fetch_row(TAOS_RES *res)

按行获取查询结果集中的数据。
int taos_fetch_block(TAOS_RES *res, TAOS_ROW *rows)

批量获取查询结果集中的数据，返回值为获取到的数据的行数。
int taos_num_fields(TAOS_RES *res) 和 int taos_field_count(TAOS_RES *res)

这两个 API 等价，用于获取查询结果集中的列数。
int* taos_fetch_lengths(TAOS_RES *res)

获取结果集中每个字段的长度。返回值是一个数组，其长度为结果集的列数。
int taos_affected_rows(TAOS_RES *res)

获取被所执行的 SQL 语句影响的行数。
TAOS_FIELD *taos_fetch_fields(TAOS_RES *res)

获取查询结果集每列数据的属性（列的名称、列的数据类型、列的长度），与 taos_num_fileds() 配合使用，可用来解析 taos_fetch_row() 返回的一个元组(一行)的数据。 TAOS_FIELD 的结构如下：

typedef struct taosField {
  char     name[65];  // column name
  uint8_t  type;      // data type
  int16_t  bytes;     // length, in bytes
} TAOS_FIELD;

void taos_stop_query(TAOS_RES *res)

停止当前查询的执行。
void taos_free_result(TAOS_RES *res)

释放查询结果集以及相关的资源。查询完成后，务必调用该 API 释放资源，否则可能导致应用内存泄露。但也需注意，释放资源后，如果再调用 taos_consume() 等获取查询结果的函数，将导致应用崩溃。
char *taos_errstr(TAOS_RES *res)

获取最近一次 API 调用失败的原因,返回值为字符串标识的错误提示信息。
int taos_errno(TAOS_RES *res)

获取最近一次 API 调用失败的原因，返回值为错误代码。

note

2.0 及以上版本 TDengine 推荐数据库应用的每个线程都建立一个独立的连接，或基于线程建立连接池。而不推荐在应用中将该连接 (TAOS*) 结构体传递到不同的线程共享使用。基于 TAOS 结构体发出的查询、写入等操作具有多线程安全性，但 “USE statement” 等状态量有可能在线程之间相互干扰。此外，C 语言的连接器可以按照需求动态建立面向数据库的新连接（该过程对用户不可见），同时建议只有在程序最后退出的时候才调用 taos_close() 关闭连接。

异步查询 API

TDengine 还提供性能更高的异步 API 处理数据插入、查询操作。在软硬件环境相同的情况下，异步 API 处理数据插入的速度比同步 API 快 2 ～ 4 倍。异步 API 采用非阻塞式的调用方式，在系统真正完成某个具体数据库操作前，立即返回。调用的线程可以去处理其他工作，从而可以提升整个应用的性能。异步 API 在网络延迟严重的情况下，优势尤为突出。

异步 API 都需要应用提供相应的回调函数，回调函数参数设置如下：前两个参数都是一致的，第三个参数依不同的 API 而定。第一个参数 param 是应用调用异步 API 时提供给系统的，用于回调时，应用能够找回具体操作的上下文，依具体实现而定。第二个参数是 SQL 操作的结果集，如果为空，比如 insert 操作，表示没有记录返回，如果不为空，比如 select 操作，表示有记录返回。

异步 API 对于使用者的要求相对较高，用户可根据具体应用场景选择性使用。下面是两个重要的异步 API：

void taos_query_a(TAOS *taos, const char *sql, void (*fp)(void *param, TAOS_RES *, int code), void *param);

异步执行 SQL 语句。
- taos：调用 taos_connect() 返回的数据库连接
- sql：需要执行的 SQL 语句
- fp：用户定义的回调函数，其第三个参数 code 用于指示操作是否成功，0 表示成功，负数表示失败（调用 taos_errstr() 可获取失败原因）。应用在定义回调函数的时候，主要处理第二个参数 TAOS_RES *，该参数是查询返回的结果集
- param：应用提供一个用于回调的参数
void taos_fetch_rows_a(TAOS_RES *res, void (*fp)(void *param, TAOS_RES *, int numOfRows), void *param);

批量获取异步查询的结果集，只能与 taos_query_a() 配合使用。其中：
- res：taos_query_a() 回调时返回的结果集
- fp：回调函数。其参数 param 是用户可定义的传递给回调函数的参数结构体；numOfRows 是获取到的数据的行数（不是整个查询结果集的函数）。在回调函数中，应用可以通过调用 taos_fetch_row() 前向迭代获取批量记录中每一行记录。读完一块内的所有记录后，应用需要在回调函数中继续调用 taos_fetch_rows_a() 获取下一批记录进行处理，直到返回的记录数 numOfRows 为零（结果返回完成）或记录数为负值（查询出错）。

TDengine 的异步 API 均采用非阻塞调用模式。应用程序可以用多线程同时打开多张表，并可以同时对每张打开的表进行查询或者插入操作。需要指出的是，客户端应用必须确保对同一张表的操作完全串行化，即对同一个表的插入或查询操作未完成时（未返回时），不能够执行第二个插入或查询操作。

参数绑定 API

除了直接调用 taos_query() 进行查询，TDengine 也提供了支持参数绑定的 Prepare API，风格与 MySQL 类似，目前也仅支持用问号 ? 来代表待绑定的参数。

从 2.1.1.0 和 2.1.2.0 版本开始，TDengine 大幅改进了参数绑定接口对数据写入（INSERT）场景的支持。这样在通过参数绑定接口写入数据时，就避免了 SQL 语法解析的资源消耗，从而在绝大多数情况下显著提升写入性能。此时的典型操作步骤如下：

调用 taos_stmt_init() 创建参数绑定对象；
调用 taos_stmt_prepare() 解析 INSERT 语句；
如果 INSERT 语句中预留了表名但没有预留 TAGS，那么调用 taos_stmt_set_tbname() 来设置表名；
如果 INSERT 语句中既预留了表名又预留了 TAGS（例如 INSERT 语句采取的是自动建表的方式），那么调用 taos_stmt_set_tbname_tags() 来设置表名和 TAGS 的值；
调用 taos_stmt_bind_param_batch() 以多行的方式设置 VALUES 的值，或者调用 taos_stmt_bind_param() 以单行的方式设置 VALUES 的值；
调用 taos_stmt_add_batch() 把当前绑定的参数加入批处理；
可以重复第 3 ～ 6 步，为批处理加入更多的数据行；
调用 taos_stmt_execute() 执行已经准备好的批处理指令；
执行完毕，调用 taos_stmt_close() 释放所有资源。

说明：如果 taos_stmt_execute() 执行成功，假如不需要改变 SQL 语句的话，那么是可以复用 taos_stmt_prepare() 的解析结果，直接进行第 3 ～ 6 步绑定新数据的。但如果执行出错，那么并不建议继续在当前的环境上下文下继续工作，而是建议释放资源，然后从 taos_stmt_init() 步骤重新开始。

接口相关的具体函数如下（也可以参考 prepare.c 文件中使用对应函数的方式）：

TAOS_STMT* taos_stmt_init(TAOS *taos)

创建一个 TAOS_STMT 对象用于后续调用。
int taos_stmt_prepare(TAOS_STMT *stmt, const char *sql, unsigned long length)

解析一条 SQL 语句，将解析结果和参数信息绑定到 stmt 上，如果参数 length 大于 0，将使用此参数作为 SQL 语句的长度，如等于 0，将自动判断 SQL 语句的长度。
int taos_stmt_bind_param(TAOS_STMT *stmt, TAOS_BIND *bind)

不如 taos_stmt_bind_param_batch() 效率高，但可以支持非 INSERT 类型的 SQL 语句。进行参数绑定，bind 指向一个数组（代表所要绑定的一行数据），需保证此数组中的元素数量和顺序与 SQL 语句中的参数完全一致。TAOS_BIND 的使用方法与 MySQL 中的 MYSQL_BIND 类似，具体定义如下：
```
typedef struct TAOS_BIND {
  int            buffer_type;
  void *         buffer;
  uintptr_t      buffer_length;  // not in use
  uintptr_t *    length;
  int *          is_null;
  int            is_unsigned;    // not in use
  int *          error;          // not in use
} TAOS_BIND;
```
int taos_stmt_set_tbname(TAOS_STMT* stmt, const char* name)

（2.1.1.0 版本新增，仅支持用于替换 INSERT 语句中的参数值）当 SQL 语句中的表名使用了 ? 占位时，可以使用此函数绑定一个具体的表名。
int taos_stmt_set_tbname_tags(TAOS_STMT* stmt, const char* name, TAOS_BIND* tags)

（2.1.2.0 版本新增，仅支持用于替换 INSERT 语句中的参数值）当 SQL 语句中的表名和 TAGS 都使用了 ? 占位时，可以使用此函数绑定具体的表名和具体的 TAGS 取值。最典型的使用场景是使用了自动建表功能的 INSERT 语句（目前版本不支持指定具体的 TAGS 列）。TAGS 参数中的列数量需要与 SQL 语句中要求的 TAGS 数量完全一致。
int taos_stmt_bind_param_batch(TAOS_STMT* stmt, TAOS_MULTI_BIND* bind)

（2.1.1.0 版本新增，仅支持用于替换 INSERT 语句中的参数值）以多列的方式传递待绑定的数据，需要保证这里传递的数据列的顺序、列的数量与 SQL 语句中的 VALUES 参数完全一致。TAOS_MULTI_BIND 的具体定义如下：
```
typedef struct TAOS_MULTI_BIND {
  int          buffer_type;
  void *       buffer;
  uintptr_t    buffer_length;
  uintptr_t *  length;
  char *       is_null;
  int          num;             // the number of columns
} TAOS_MULTI_BIND;
```
int taos_stmt_add_batch(TAOS_STMT *stmt)

将当前绑定的参数加入批处理中，调用此函数后，可以再次调用 taos_stmt_bind_param() 或 taos_stmt_bind_param_batch() 绑定新的参数。需要注意，此函数仅支持 INSERT/IMPORT 语句，如果是 SELECT 等其他 SQL 语句，将返回错误。
int taos_stmt_execute(TAOS_STMT *stmt)

执行准备好的语句。目前，一条语句只能执行一次。
TAOS_RES* taos_stmt_use_result(TAOS_STMT *stmt)

获取语句的结果集。结果集的使用方式与非参数化调用时一致，使用完成后，应对此结果集调用 taos_free_result() 以释放资源。
int taos_stmt_close(TAOS_STMT *stmt)

执行完毕，释放所有资源。
char * taos_stmt_errstr(TAOS_STMT *stmt)

（2.1.3.0 版本新增）用于在其他 STMT API 返回错误（返回错误码或空指针）时获取错误信息。

无模式（schemaless）写入 API

除了使用 SQL 方式或者使用参数绑定 API 写入数据外，还可以使用 Schemaless 的方式完成写入。Schemaless 可以免于预先创建超级表/数据子表的数据结构，而是可以直接写入数据，TDengine 系统会根据写入的数据内容自动创建和维护所需要的表结构。Schemaless 的使用方式详见 Schemaless 写入章节，这里介绍与之配套使用的 C/C++ API。

TAOS_RES* taos_schemaless_insert(TAOS* taos, const char* lines[], int numLines, int protocol, int precision)

功能说明 该接口将行协议的文本数据写入到 TDengine 中。

参数说明 taos: 数据库连接，通过 taos_connect() 函数建立的数据库连接。 lines：文本数据。满足解析格式要求的无模式文本字符串。 numLines:文本数据的行数，不能为 0 。 protocol: 行协议类型，用于标识文本数据格式。 precision：文本数据中的时间戳精度字符串。

返回值 TAOS_RES 结构体，应用可以通过使用 taos_errstr() 获得错误信息，也可以使用 taos_errno() 获得错误码。在某些情况下，返回的 TAOS_RES 为 NULL，此时仍然可以调用 taos_errno() 来安全地获得错误码信息。返回的 TAOS_RES 需要调用方来负责释放，否则会出现内存泄漏。

说明协议类型是枚举类型，包含以下三种格式：
- TSDB_SML_LINE_PROTOCOL：InfluxDB 行协议（Line Protocol)
- TSDB_SML_TELNET_PROTOCOL: OpenTSDB Telnet 文本行协议
- TSDB_SML_JSON_PROTOCOL: OpenTSDB Json 协议格式
时间戳分辨率的定义，定义在 taos.h 文件中，具体内容如下：
- TSDB_SML_TIMESTAMP_NOT_CONFIGURED = 0,
- TSDB_SML_TIMESTAMP_HOURS,
- TSDB_SML_TIMESTAMP_MINUTES,
- TSDB_SML_TIMESTAMP_SECONDS,
- TSDB_SML_TIMESTAMP_MILLI_SECONDS,
- TSDB_SML_TIMESTAMP_MICRO_SECONDS,
- TSDB_SML_TIMESTAMP_NANO_SECONDS
需要注意的是，时间戳分辨率参数只在协议类型为 SML_LINE_PROTOCOL 的时候生效。对于 OpenTSDB 的文本协议，时间戳的解析遵循其官方解析规则 — 按照时间戳包含的字符的数量来确认时间精度。

支持版本 该功能接口从 2.3.0.0 版本开始支持。

订阅和消费 API

订阅 API 目前支持订阅一张或多张表，并通过定期轮询的方式不断获取写入表中的最新数据。

TAOS_SUB *taos_subscribe(TAOS* taos, int restart, const char* topic, const char *sql, TAOS_SUBSCRIBE_CALLBACK fp, void *param, int interval)

该函数负责启动订阅服务，成功时返回订阅对象，失败时返回 NULL，其参数为：
- taos：已经建立好的数据库连接
- restart：如果订阅已经存在，是重新开始，还是继续之前的订阅
- topic：订阅的主题（即名称），此参数是订阅的唯一标识
- sql：订阅的查询语句，此语句只能是 select 语句，只应查询原始数据，只能按时间正序查询数据
- fp：收到查询结果时的回调函数（稍后介绍函数原型），只在异步调用时使用，同步调用时此参数应该传 NULL
- param：调用回调函数时的附加参数，系统 API 将其原样传递到回调函数，不进行任何处理
- interval：轮询周期，单位为毫秒。异步调用时，将根据此参数周期性的调用回调函数，为避免对系统性能造成影响，不建议将此参数设置的过小；同步调用时，如两次调用 taos_consume() 的间隔小于此周期，API 将会阻塞，直到时间间隔超过此周期。
typedef void (*TAOS_SUBSCRIBE_CALLBACK)(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code)

异步模式下，回调函数的原型，其参数为：
- tsub：订阅对象
- res：查询结果集，注意结果集中可能没有记录
- param：调用 taos_subscribe() 时客户程序提供的附加参数
- code：错误码
note
在这个回调函数里不可以做耗时过长的处理，尤其是对于返回的结果集中数据较多的情况，否则有可能导致客户端阻塞等异常状态。如果必须进行复杂计算，则建议在另外的线程中进行处理。
TAOS_RES *taos_consume(TAOS_SUB *tsub)

同步模式下，该函数用来获取订阅的结果。用户应用程序将其置于一个循环之中。如两次调用 taos_consume() 的间隔小于订阅的轮询周期，API 将会阻塞，直到时间间隔超过此周期。如果数据库有新记录到达，该 API 将返回该最新的记录，否则返回一个没有记录的空结果集。如果返回值为 NULL，说明系统出错。异步模式下，用户程序不应调用此 API。

note
在调用 taos_consume() 之后，用户应用应确保尽快调用 taos_fetch_row() 或 taos_fetch_block() 来处理订阅结果，否则服务端会持续缓存查询结果数据等待客户端读取，极端情况下会导致服务端内存消耗殆尽，影响服务稳定性。
void taos_unsubscribe(TAOS_SUB *tsub, int keepProgress)

取消订阅。如参数 keepProgress 不为 0，API 会保留订阅的进度信息，后续调用 taos_subscribe() 时可以基于此进度继续；否则将删除进度信息，后续只能重新开始读取数据。

支持的平台​

支持的版本​

安装步骤​

建立连接​

示例程序​

同步查询示例​

异步查询示例​

参数绑定示例​

无模式写入示例​

订阅和消费示例​

API 参考​

基础 API​

同步查询 API​

异步查询 API​

参数绑定 API​

无模式（schemaless）写入 API​

订阅和消费 API​

支持和反馈

支持的平台

支持的版本

安装步骤

建立连接

示例程序

同步查询示例

异步查询示例

参数绑定示例

无模式写入示例

订阅和消费示例

API 参考

基础 API

同步查询 API

异步查询 API

参数绑定 API

无模式（schemaless）写入 API

订阅和消费 API