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the main reason requinix stated that is because you are not validating input data before using it (which i have mentioned doing multiple times in this thread.) someone can cause your code to execute any php function, like phpinfo(), by simply setting $_GET['form_type'] to phpinfo when they request your page. do you really want someone to be able to see the phpinfo output from your site or execute any php function? your code needs to have direct, positive control over what gets executed on any page request.

I created an extra table to define which category the values were in mysql> select * from catval; +-----+------+ | val | cat | +-----+------+ | 1 | 4 | | 2 | 4 | | 3 | 4 | | 4 | 4 | | 5 | 3 | | 6 | 3 | | 7 | 2 | | 8 | 2 | | 9 | 1 | | 10 | 1 | +-----+------+ then $sql = "SELECT a.cat as cata , b.cat as catb FROM datatb d JOIN catval a ON d.grpa = a.val JOIN catval b ON d.grpb = b.val "; $result = $db->query($sql); //categories $cat = [ 4 => ['name'=>'1:4', 'recs'=>[]], 3 => ['name'=>'5:6', 'recs'=>[]], 2 => ['name'=>'7:8', 'recs'=>[]], 1 => ['name'=>'9:10','recs'=>[]] ]; $n = 0; while ($row = $result->fetch_assoc()) { $cat[$row['cata']]['recs'][$n][] = $row['cata']; $cat[$row['catb']]['recs'][$n][] = $row['catb']; $n++; } // the output echo "<table border='1' style='width:500px; border-collapse:collapse;'>"; foreach ($cat as $c) { echo "<tr><th>{$c['name']}</th>"; for ($i=0; $i<$n; $i++) { echo '<td style="text-align:center;">' . (isset($c['recs'][$i]) ? join(',', $c['recs'][$i]) : '&ndash;') . "</td>"; } echo "</tr>\n"; } echo "</table>\n";

I enjoy the challenge when someone posts a problem I can get my teeth into.

One way is... $secs = 350000; $dt1 = new DateTime(); $dt2 = (clone $dt1)->add(new DateInterval('PT'.$secs.'S')); $diff = $dt1->diff($dt2); echo $diff->days . ' : ' . $diff->format('%h : %i : %s').'<br>'; //-> 4 : 1 : 13 : 20