显示数据库值的总和 - PHP

Hi I need to get the sum of the database field sbstart. I changed the code to SUM(sbstart) but doesn't seems to be a valid move. How can I display the sum? Thanks.

        <?php


$host = 'localhost';
$user = 'root';
$pass = '';
$db = 'regional_data';
@ $db = mysqli_connect($host, $user, $pass, $db);

if(mysqli_connect_errno())
{
    die('The connection to the database could not be established.');
}
$query = "SELECT SUM(sbstart) FROM newchk WHERE dist_chk ='$distUsr'";
$result = mysqli_query($db, $query);

while ($recS = mysqli_fetch_array($result)){

echo ($recS['sbstart']);    
}
?>

Change

$query = "SELECT SUM(sbstart) FROM newchk WHERE dist_chk ='$distUsr'";

To (Use alias)

$query = "SELECT SUM(sbstart) as sub FROM newchk WHERE dist_chk ='$distUsr'";

Then

you doesn't need while loop because it return only one result.

$recS = mysqli_fetch_array($result);
echo $recS['sub'];

You need to use either mysqli_fetch_assoc instead of mysql_fetch_array, or you need to do echo $recS[0].

Change

$query = "SELECT SUM(sbstart) FROM newchk WHERE dist_chk ='$distUsr'";

to

$query = "SELECT SUM(sbstart) AS sum FROM newchk WHERE dist_chk ='$distUsr'";

and change

echo ($recS['sbstart']);

to

echo ($recS['sum']);