MySQLi Sum

MySQLi SUM is used to return the total summed value of an expression.

Below the syntax of SUM function.

SELECT SUM(aggregate_expression) FROM table_name [conditions];
  $conn  = mysqli_connect('localhost:3306', 'user_name', 'password', 'db_nexladder');
  if(! $conn) {
     die('Could not connect: ' . mysqli_error());
  $sql = "SELECT SUM(`working_hours`) AS total_working_hours FROM `tbl_employee`";
  $result = mysqli_query($conn, $sql);
  $row = mysqli_fetch_object($result) ;
  echo "Total Working Hours: " . $row->total_working_hours;

Below it'll look like with SUM Aggregate

mysql sum