C/C++ 下mysql应用封装（连接增删改查）

mysql - 初始化

1. mysql_init():初始化数据库
2. mysql_real_connect()(不推荐用Mysql_connect())：连接数据库
   
   详细代码如下：

bool dataBase::initConnection()
{
	try
	{
        if (mysql_init(&m_sqlCon) == NULL)
        {
            std::cout << "初始化数据库失败" << std::endl;
            return false;
        }
        // localhost:服务器 root为账号密码 test为数据库名 3306为端口
        if (!mysql_real_connect(&m_sqlCon, host, user, pass,databaseName, port, NULL, 0))
        {
           std::cout << "数据库连接失败" << std::endl;
           return false;
       }
       std::cout << "数据库连接成功" << std::endl;
       return true;
   }
   catch (...)
   {
       std::cout << "出错啦" << std::endl;
       return false;
  }
}

mysql - 查

1）mysql_query()：进行查询语句

2）mysql_store_result()：获得查询结果

3 ) mysql_fetch_field()以及mysql_fetch_row()：获得结果集中的内容

4）mysql_free_result()

代码如下：

void dataBase::user_query(
{
	if (mysql_query(&m_sqlCon, "select * from user"))
	{
		std::cout << "查询失败" << std::endl;
		return;
	}
	std::cout << "查询成功" << std::endl;

	MYSQL_RES *result;
	result = mysql_store_result(&m_sqlCon);
	if (result)
	{
		int row_num, col_num;
		row_num = mysql_num_rows(result);
		col_num = mysql_num_fields(result);
		std::cout << "共有" << row_num << "条数据，以下为其详细内容：" << std::endl;
		MYSQL_FIELD *fd;

		while (fd = mysql_fetch_field(result))
		{
			std::cout << fd->name << "\t";
		}
		std::cout << std::endl;
		MYSQL_ROW sql_row;

		while (sql_row = mysql_fetch_row(result))
		{
			for (int i = 0; i < col_num; i++)
			{
				if (sql_row[i] == NULL) std::cout << "NULL\t";
				else std::cout << sql_row[i] << "\t";
			}
			std::cout << std::endl;
		}
	}

	if (result != NULL)
		mysql_free_result(result);

}

mysql - 增

1）mysql_query()通过select判断是否已经存在（可以省略）

2 ) 通过mysql_query()进行插入

代码如下：

void dataBase::user_insert(UserBody &body)
{
	char select_user[255];
	char query[255];
	MYSQL_RES *result;
	sprintf(select_user, "select * from user where UserName='%s'", body.userName);
	if (mysql_query(&m_sqlCon, select_user) || !(result = mysql_store_result(&m_sqlCon)))
	{
		std::cout << "插入查询失败" << std::endl;
		return;
	}

	if (mysql_num_rows(result))
	{
		std::cout << "用户已存在" << std::endl;
		mysql_free_result(result);
		return;
	}

	mysql_free_result(result);
	sprintf(query, "insert into user(UserName,UserPass,ConnectionNum,UseFor) values('%s','%s',%d,%d)", body.userName, body.userPass, body.connection, body.type);
	if (mysql_query(&m_sqlCon, query))
	{
		std::cout << "插入数据失败" << std::endl;
		return;
	}
	std::cout << "插入数据成功,共插入：" << mysql_affected_rows(&m_sqlCon) << "行" << std::endl;
}

mysql - 改

修改与添加的步骤类似，直接贴出代码就不做赘述了。

代码如下：

void dataBase::user_update(UserBody &body)
{
	char query[255];
	char select_user[255];
	MYSQL_RES *result;
	sprintf(select_user, "select * from user where UserName='%s'", body.userName);
	if (mysql_query(&m_sqlCon, select_user) || !(result = mysql_store_result(&m_sqlCon)))
	{
		std::cout << "修改查询失败" << std::endl;
		return;
	}

	if (mysql_num_rows(result) == 0) {
		std::cout << "要修改的用户不存在" << std::endl;
		mysql_free_result(result);
		return;
	}

	mysql_free_result(result);
	sprintf(query, "update user set UserPass='%s',ConnectionNum=%d,UseFor=%d where UserName='%s'", body.userPass, body.connection, body.type, body.userName);
	if (mysql_query(&m_sqlCon, query))
	{
		std::cout << "修改失败" << std::endl;
		return;
	}
	std::cout << "修改成功，共修改：" << mysql_affected_rows(&m_sqlCon) << "行" << std::endl;
}

mysql - 删

其实删除、修改和插入操作都是类似的，会其中一个其他应该都差不多了，我也就直接贴出代码了。

代码如下：

void dataBase::user_delete(char *userName)
{
	char query[255];
	char select_user[255];
	MYSQL_RES *result;
	sprintf(select_user, "select * from user where UserName='%s'", userName);
	if (mysql_query(&m_sqlCon, select_user) || !(result = mysql_store_result(&m_sqlCon)))
	{
		std::cout << "删除查询失败" << std::endl;
		return;
	}

	if (mysql_num_rows(result) == 0)
	{
		std::cout << "要删除的用户不存在" << std::endl;
		mysql_free_result(result);
		return;
	}

	mysql_free_result(result);
	sprintf(query, "delete from user where UserName='%s'", userName);
	if (mysql_query(&m_sqlCon, query))
	{
		std::cout << "删除失败" << std::endl;
		return;
	}
	std::cout << "删除成功，共删除：" << mysql_affected_rows(&m_sqlCon) << "行" << std::endl;
}