LR从数据库中返回值

/*需要的表结构如下
CREATE TABLE `test_data` (
  `order_id` BIGINT UNSIGNED NOT NULL COMMENT 'Order numbers. Must be unique.',
  `status` BOOL NOT NULL DEFAULT '0' COMMENT 'Whether data has been used or not. A value of 0 means FALSE.',
  `date_used` DATETIME NULL COMMENT 'Date/time that the data was used.',
  UNIQUE (
    `order_id`
  )
) ENGINE = innodb COMMENT = 'LoadRunner test data';
*/
Action()
{
  int rc;
  int db_connection; // 数据库连接
  int query_result; // 查询结果集 MYSQL_RES
  char** result_row; // 查询的数据行
 
  char *server = "192.168.2.200";
  char *user = "root";
  char *password = "*******";
  char *database = "*****";
  int port = 3306;
  int unix_socket = NULL;
  int flags = 0;
 
  // 找到libmysql.dll的所在位置.
  rc = lr_load_dll("d:\\libmysql.dll");
  if (rc != 0) {
    lr_error_message("Could not load libmysql.dll");
    lr_abort();
  }
 
  // 创建MySQL对象
  db_connection = mysql_init(NULL);
  if (db_connection == NULL) {
    lr_error_message("Insufficient memory");
    lr_abort();
  }
 
  // 连接到MySQL数据库
  rc = mysql_real_connect(db_connection, server, user, password, database, port, unix_socket, flags);
  if (rc == NULL) {
    lr_error_message("%s", mysql_error(db_connection));
    mysql_close(db_connection);
    lr_abort();
  }

 rc = mysql_query(db_connection, "SELECT order_id FROM test_data WHERE status=1 LIMIT 1");
  if (rc != 0) {
    lr_error_message("%s", mysql_error(db_connection));
    mysql_close(db_connection);
    lr_abort();
  }
  query_result = mysql_use_result(db_connection);
  if (query_result == NULL) {
    lr_error_message("%s", mysql_error(db_connection));
    mysql_free_result(query_result);
    mysql_close(db_connection);
    lr_abort();
  }
  result_row = (char **)mysql_fetch_row(query_result);
  if (result_row == NULL) {
    lr_error_message("Did not expect the result set to be empty");
    mysql_free_result(query_result);
    mysql_close(db_connection);
    lr_abort();
  }
  lr_save_string(result_row[0], "paramOrderID");
  lr_output_message("Order ID is: %s", lr_eval_string("{paramOrderID}"));
  mysql_free_result(query_result);

  mysql_close(db_connection);

}