[c++ 使用mysql]#mysql #c++

0-project.md

如何添加到工程

---

一、下载mysql connect c 6.0

最新版本整合进大安装包了，6.0以下有单独的client dev mysql connect c 6.0 或者直接apt 安装

sudo apt install libmysqlclient-dev

二、如果是下载的

• 1.解压压缩包
• 2.包含头文件
• 3.链接库 libmysqlclient.so cmake

set(MYSQL mysql-connector-c-6.1.11-linux-glibc2.12-x86_64)
include_directories(thirdparty/include/${MYSQL})
link_directories(thirdparty/lib/${MYSQL})

add_executable(${PROJECT} ${DIR_SRCS}
)

target_link_libraries(${PROJECT} pthread hcnetsdk HCAlarm ssl z log4cplus  mysqlclient)

1-connect.cpp

  //connect
  MYSQL *Connect() {
    MYSQL* mysql = mysql_init(nullptr);
    if (mysql == nullptr) {
      LOG_ERROR("mysql init error:%s", mysql_error(mysql));
      return nullptr;
    }

    auto conn =
        mysql_real_connect(mysql, host.c_str(), user.c_str(), passwd.c_str(),
                           db.c_str(), port, nullptr, 0);
    if (conn == nullptr) {
      LOG_ERROR("mysql connect error:%s", mysql_error(mysql));
      return nullptr;
    }
    return conn;
  }

//不用之后需要close
  auto conn = Connect();
  if (conn == nullptr){
    return false;
  }
  DEFER{mysql_close(conn);};

2-insert.cpp

  auto conn = Connect();
  if (conn == nullptr){
    return false;
  }
  DEFER{mysql_close(conn);};
  
  char query[1024];

  sprintf(query,"INSERT INTO table_name (value1,value2,...) VALUES (%s,%s,%s,...)",value1,value2,value3);
  auto ret = mysql_query(conn, query);
  if (ret != 0) {
    LOG_ERROR("mysql insert  error,sql:%s \n error:%s", query, mysql_error(conn));
    return false;
  }
  return true;

3-select.cpp

  auto conn = impl->Connect();
  if (conn == nullptr) {
    return false;
  }
  DEFER { mysql_close(conn); };

  char query[1024];
  sprintf(query, "SELECT * FROM table_name", limit);
  auto ret = mysql_query(conn, query);
  if (ret != 0) {
    LOG_ERROR("mysql select error ,sql :%s \n error:%s", query, mysql_error(conn));
    return false;
  }
  MYSQL_RES *result = mysql_store_result(conn);
  if (result == nullptr){
    LOG_ERROR("mysql store result error :%s",mysql_error(conn));
    return false;
  }
  DEFER{mysql_free_result(result);};
  
  auto num_rows = mysql_num_rows(result);
  LOG_INFO("got %d row verify info ",(int)num_rows);

  unsigned int num_fields = mysql_num_fields(result);
  
  MYSQL_ROW row;
  while (row = mysql_fetch_row(result))
  {
    unsigned long *lengths = mysql_fetch_lengths(result);
    
    for (int i = 0; i < num_fields; i++)
    {
      char *filed = row[i];
      unsigned int field_length = lengths[i];
      LOG_INFO("column[%d],length[%d],data[%s]\n", i, field_length, filed ? filed : "null");
    }
  }


  return false;