使总数等于以分钟和秒为单位的数量

以下代码从数据库中获取人们的圈数"时间"。我希望它的总和为分钟和秒，因为它目前只显示一个数字。

<?php
    //MySqli Select Query
    $results = $mysqli->query("SELECT *, (r1 + r2 + r3 + r4 + r5) AS total FROM test WHERE event = '1' ORDER BY total DESC");
    $title = $mysqli->query("SELECT * FROM test");
    $all_cols=array("rt1" => "r1","rt2"=> "r2","rt3"=> "r3","rt4"=> "r4","rt5"=> "r5");
    while ($t = $title->fetch_assoc()){
        // remember empty cols
        $empty_cols=array();
        echo "<table width='"1000'" cellpadding='"5'" cellspacing='2'" class='"entrywriting'" align='"center'">
        <tr align='"center'">
        <td>Overall</td>
        <td>Competitor</td>";
        foreach ($all_cols as $col => $value) {
            if (!empty($t[$col])) {
                echo "<td>" . $t[$col] . "</td>";
            } else {
                // set this column as empty for later
                $empty_cols[]=$col;
            }
        } unset($col); unset($value);
        echo "
        <td>Total</td>
        </tr>";
    }
    //set counter
    $counter = 1;
    while($row = $results->fetch_assoc()) {
        echo "<tr align='"center'">";
        echo "<td>" . $counter . "</td>";
        echo '<td>'.$row["driver"].'</td>';
        foreach ($all_cols as $col => $value) {
            if (!in_array($col, $empty_cols)) {
                // echo non-empty values
                echo '<td>'.$row[$value].'</td>';
            }
        } unset($col); unset($value);
        echo '<td>'.$row["total"].'</td>';
        $counter++; //increment count by 1
    }  
    echo "</table>";
    ?>

我怎样才能达到分钟和秒的总和？R1 - R5 是圈数的实际时间，所以让我们说

lap 1 = 00:01:01
lap 2 = 00:00:59
lap 3 = 00:00:45
this would be a total of: 00:02:45 HH:MM:SS

rt1 - rt5 是路线或圈数。

所以我想要 r1 + r2 + r3 + r4 + r5 总计 = HH：MM：SS 数据库设置为时间。