如何通过降序排列前五列总和？

I've a table like this:

---------------------------------------
| S No | item     | Col1      | Col2  |
| ------------------------------------|
| 1    | carrot   | 111       | 2     |
| 2    | broccoli | 222       | 3     |
| 3    | spinach  | 333       | 2     |
| 4    | swiss    | 444       | 3     |
| 5    | cheddar  | 5555      | 5     |
| 6    | cheddar  | 6666      | 6     |
| 7    | onion    | 7777      | 3     |

There are many columns like Col1, Col2, Coln with all integer values. I want to take sum of all columns and get the name of top 5 columns with their names and sum values as response of query. I can do this with top 5 records but find it hard to do with columns. I'm doing it for rows like this:

$q1 = mysqli_query($con, "SELECT `File Name`, `Kudos` FROM `{$_SESSION['username']}` ORDER BY `Kudos` DESC LIMIT 5");

while($row = mysqli_fetch_array($q1)) {
    $myCols[] = $row;
} 
print_r($myCols); // Works fine

print_r gives me:

Array
(
    [0] => Array
        (
            [0] => AAAA
            [File Name] => AAAA
            [1] => 343
            [Kudos] => 343
        )

    [1] => Array
        (
            [0] => Test File Again
            [File Name] => Test File Again
            [1] => 45
            [Kudos] => 45
        )

    [2] => Array
        (
            [0] => TEST FILE
            [File Name] => TEST FILE
            [1] => 3
            [Kudos] => 3
        )

)

Looks good. How do I same for column with maximum sum values for whole column? Anyone out there? Thanks!

Just add them up and use them in the order by:

SELECT `File Name`, (col1 + col2 + col3 . . . ) as totalsum
FROM `{$_SESSION['username']}
ORDER BY totalsum DESC
LIMIT 5;