Comparing MySQL results to each other, while putting them in a table

I have a table that looks like this:

(so you can picture it visual开发者_开发知识库ly)

13  22  12
10  8   12

html:

<table>
    <tr>
        <td>13</td>
        <td>22</td>
        <td>12</td>
    <tr>
        <td>10</td>
        <td>8</td>
        <td>12</td>
    </tr>
</table>

it's being populated by mysql rows:

<?php
    $i = 1;
    $id = mysql_fetch_assoc(mysql_query("SELECT `id` FROM `users` WHERE `username` = '".$_GET['user']."'"));
    $query = mysql_query("SELECT * FROM `data` WHERE `user_id` = '".$id['id']."' ORDER BY `datetime` DESC");
    while($row = mysql_fetch_assoc($query)) {
        echo '<tr><td>'.date('m/d H:i', strtotime($row['datetime'])).'</td>';
        array_shift($row);
        array_shift($row);
        array_shift($row);
        $new = array_chunk($row, 3);
        foreach($new as $value => $var) {
            if($var[1] == null) { $var[1] = "--"; }
                echo '<td id="'.$i++.'">'.$var[1].'</td>';  
                }
        echo '</tr>';
    }

?>

If I wanted to have the each row compare itself to the row above it, and then do something (such as change font color or <td> background color), how would I do that? For example, the 13 and 22 would change to boldface or red or something, and the 12's not change.

you can keep track of the previous row by setting $prev = $row at the end of the loop, then compare against prev, $color = ($prev && $row['x'] > $prev['x']) ? 'green' : 'red';

for something more advanced you can get all the rows into an array first: $rows = array(); while ($row = mysql_fetch_assoc($result)){ $rows[] = $row; }