Mysql while循环加起来数字

    $oneweek = date("Y-m-d",strtotime("-1 week"));
    $currentdate = date("Y-m-d");

    $result = mysqli_query($con, "SELECT * FROM `76561198047786230` WHERE date >= '$oneweek' AND date <= '$currentdate'");


 while($row = mysqli_fetch_array($result)) {
            echo $row['start'];
            }



id start  end          date
2   22  23:18   2014-07-03 22:09:16
3   3   03:43   2014-07-04 03:09:10
4   12  13:38   2014-07-04 12:04:19
5   14  16:43   2014-07-04 14:08:53

My table looks like this ^

when i run that while loop it will gather these data

22
3
12
14

My question is since it does it in a loop it echoes it out separetly so how can i take all those values and add them up so 22 + 3 + 12 + 14 = 51?

Try something like following:

$count = 0;
while($row = mysqli_fetch_array($result)) 
{
   $count += $row['start'];
}

echo $count; // 51

http://www.w3schools.com/sql/sql_func_sum.asp

SELECT SUM(column_name) FROM table_name;