1、在LXMysql.h和LXMysql.cpp分别定义和编写关于pin语句的代码

//获取更新数据的sql语句 where语句中用户要包含where 更新
	std::string GetUpdatesql(XDATA kv, std::string table, std::string where);

std::string LXMysql::GetUpdatesql(XDATA kv, std::string table, std::string where)
	{
		string sql = "";
		if (kv.empty() || table.empty())
		{
			return "";
		}
		//update t_vedio set name= 'update001', size=1000 where id =10;
		sql = "update `";
		sql += table;
		sql += "` set ";
		for (auto ptr = kv.begin(); ptr != kv.end();ptr++)
		{
			sql += "`";
			sql += ptr->first;
			sql += "`=' ";
			sql += ptr->second.data;
			sql += "',";
		}
		//去除多余的逗号
		sql[sql.size() - 1] = ' ';
		sql += " ";
		sql += where;
		return sql;
	}

2、编写update代码

//返回更新数量，失败返回-1
	int Update(XDATA kv, std::string table, std::string where);

int LXMysql::Update(XDATA kv, std::string table, std::string where)
	{
		if (!mysql)
		{
			return -1;
		}
		string sql = GetUpdatesql(kv, table, where);
		if (sql.empty())
		{
			return -1;
		}
		if (!Query(sql.c_str()))
		{
			return -1;
		}
		return mysql_affected_rows(mysql);
	}

3、测试

    //更新数据
    //修改id=2的数据
    XDATA udata;
    udata["name"] = "update002";
    cout << " my.Update=" << my.Update(udata, "t_vedio", "where id=2") << endl;