1、在LXMysql.h和LXMysql.cpp分别定义和编写关于pin语句的代码
cpp
//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);
cpp
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、在LXMysql.h和LXMysql.cpp分别定义和编写UpdateBin 插入二进制数据
cpp
//返回更新数量,失败返回-1
int UpdateBin(XDATA kv, std::string table, std::string where);
cpp
int LXMysql::UpdateBin(XDATA kv, std::string table, std::string where)
{
if (!mysql || kv.empty() || table.empty())
{
return -1;
}
//update t_vedio set name= 'update001', size=1000 where id =10;
string sql = "";
sql = "update `";
sql += table;
sql += "` set ";
MYSQL_BIND bind[256] = { 0 };
int i = 0;
for (auto ptr = kv.begin(); ptr != kv.end();ptr++)
{
sql += "`";
sql += ptr->first;
sql += "`=?,";
bind[i].buffer = (char*)ptr->second.data;
bind[i].buffer_length = ptr->second.size;
//强转
bind[i].buffer_type = (enum_field_types)ptr->second.type;
i++;
}
//去除多余的逗号
sql[sql.size() - 1] = ' ';
sql += " ";
sql += where;
//预处理sql语句 上下文
MYSQL_STMT* stmt = mysql_stmt_init(mysql);
if (!stmt)
{
cerr << "mysql_stmt_init failed " << mysql_error(mysql) << endl;
return -1;
}
if (mysql_stmt_prepare(stmt, sql.c_str(), sql.length()))
{
mysql_stmt_close(stmt);
cerr << "mysql_stmt_prepare failed " << mysql_stmt_error(stmt) << endl;
return -1;
}
//绑定
if (mysql_stmt_bind_param(stmt, bind) != 0)
{
mysql_stmt_close(stmt);
cerr << "mysql_stmt_bind_param failed " << mysql_stmt_error(stmt) << endl;
return false;
}
//执行
if (mysql_stmt_execute(stmt) != 0)
{
mysql_stmt_close(stmt);
cerr << "mysql_stmt_execute failed " << mysql_stmt_error(stmt) << endl;
return -1;
}
mysql_stmt_close(stmt);
return mysql_stmt_affected_rows(stmt);
}
3、测试
cpp
//更新二进制数据
//修改id=3的图片
XDATA udata2;
LXData file2;
file2.LoadFile("F:/Documents/Desktop/c++/数据库plus/src/bin/test2.jpg");
udata2["data"] = file2;
cout << " my.UpdateBin=" << my.UpdateBin(udata2, "t_vedio", "where id=3") << endl;
file2.Drop();