#include <stdio.h>   
#include <stdlib.h>
#include <iostream> // std::cout
#include "/usr/include/mysql/mysql.h"

MYSQL* con;           //  connection
MYSQL_RES* query_results; //  result set
MYSQL_STMT* stmt;          //  prepared statement

int main() {
    unsigned long real_length = 0;
    int rc, e; std::string msg; char buf[100];
    MYSQL_BIND bind[2];
    con = mysql_init(NULL);
    if (mysql_real_connect(con, "localhost", "danny", "danny13", "test", 0, "/run/mysql/mysql.sock", 0) == NULL)
                    {printf("bad connection\n"); return 1;}
    std::string q = "SELECT `data` FROM `test`.`Temp` WHERE NOT ISNULL(data);";
    bind[0].buffer= 0;
    bind[0].buffer_length= 0;
    bind[0].length= &real_length;
    stmt = mysql_stmt_init(con); {e = mysql_errno(con); msg = mysql_error(con);}
    if (mysql_stmt_prepare(stmt, q.c_str(), q.length())) {e = mysql_errno(con); msg = mysql_error(con);}
    if (mysql_stmt_execute(stmt)) {e = mysql_errno(con); msg = mysql_error(con);}

    while (!(rc = mysql_stmt_fetch(stmt)))
    {
        if (mysql_stmt_bind_result(stmt, bind)) {e = mysql_errno(con); msg = mysql_error(con);}
        if (real_length > 0)    //  is never set to field length
        {
            char* data= (char*) malloc(real_length);
            bind[0].buffer= data;
            bind[0].buffer_length= real_length;
            mysql_stmt_fetch_column(stmt, bind, 0, 0);
        }
    }
    if (rc == 1) {e = mysql_errno(con); msg = mysql_error(con);}
}