Calculate different value from MySQL table using PHP

one text

Solution:

$weights = [];
$total_weight = 0;

while ($row = $result->fetch_assoc) {
    $item_weight = $row['quantity'] * $row['weight'];
    $total_weight += $item_weight;
    if (isset($weights[$row['seller']])) {
        $weights[$row['seller']] += $item_weight;
    } else {
        $weights[$row['seller']] = $item_weight;
    }
}
echo "Total weight = $total_weight<br>";
print_r($weights);