Get checked checkboxes in PHP

I can't get the input of checkboxes in PHP. Here is my code:

echo "<table>";

while ($zeile = mysqli_fetch_array( $ergebnis, MYSQLI_ASSOC )){
    echo "<tr>";
    echo "<td> <input type='checkbox' name='check_list[]' id='".$zeile['AGName']."'/> </td>";
    echo "<td>". $zeile['AGName'] . "</td>";
    echo "</tr>";
}

echo "</table>";

#this is the part that probably isn't correct.
if(!empty($_POST['check_list'])){
    $checked_count = count($_POST['check_list']);
    echo "You have selected following ".$checked_count." option(s): <br/>";
}

I would like to get the amount of checkboxes checked. The checkboxes are created in a loop with the input of a database. Even if this would work, how would I get the id of all of the checked checkboxes?