Calculate sum and percentage from MySQL with PHP

Question

I need to calculate the sum of missing hours at an internship and then display said sum in percentage. For example: in this case, the internship has 400 hours and somebody was missing 2 times for 5 hours (sum would be 10), so the percentage would display 2,5.

Sum	Percentage
10	2,5%

Right now, I only have how to calculate and display the sum, but don't know how to show the percentage of said sum. Here is the PHP code I have so far:

$sql = "SELECT SUM(`fehlzeit`) as 'summe' FROM fehlzeiten WHERE `praktikumsartkuerzel`= 'AP' ";

$result = $conn-> query($sql);

if ($result-> num_rows > 0) {
while ($row = $result-> fetch_assoc()) {
    echo "<tr><td>". $row["summe"] ."</td></tr>";
         }
               echo "</table>";
         }
         else {
               echo "0 result";
         }
         $conn-> close();

This is the code I tried, but it didn't work:

   $sql = "SELECT SUM(`fehlzeit`) as 'summe' FROM fehlzeiten WHERE `praktikumsartkuerzel`= 'AP' ";
    $result = $conn-> query($sql);
    $allowed = 400;
    
    if ($result-> num_rows > 0) {
        while ($row = $result-> fetch_assoc()) {
            echo "<tr><td>". $row["summe"] ."</td></tr>";
                 }
                       echo "</table>";
                 }
                 else {
                       echo "0 result";
                 }
    $procent = $result / $allowed;
    echo $procent;      
    $conn-> close();

For non-German speakers: fehlzeit means absenteeism, praktikumsartkuerzel means Type of internship abbreviation, summe means sum.

Thank you for the help in advance.

Answer 1

If you want your percent to appear in your HTML table, you should replace this

echo "<tr><td>". $row["summe"] ."</td></tr>";

with this

echo "<tr><td>". $row["summe"] ."</td><td>". $row["summe"] / $allowed ."</td> </tr>";

putting two <td> ... </td> columns in the row.