JPGraph - PHP - MySQL - 0 value

I would like to show 2 lines in the same graph that contains datas from MySQL database. I've got FAIL and DONE results in every half an hour and I would like to show the last day results.

data_time >= now() - INTERVAL 1 DAY";

Sometimes there are NO FAILs and that's why the graph can't show the right results, because it shows datas continously and don't care about the x axis.

How can I add the x variable (where no FAIL in that time period), that show 0 in these cases ? Or how can I combine the two x axis values (hours) on the same graph ?

Thanks for your help

Solution

for ($i = 0; $i <= count($data)-1; $i++) {
$k = 0;
for ($j = 0; $j <= count($data2)-1; $j++) {

    if($leg[$i] == $leg2[$j]){$data3[$i] = $data2[$j]; $k++;}
    if($k==0){$data3[$i] = 'x';}

}
}