php จะนำค่าเลขในฐานข้อมูล มาบวกกันทำยังไงครับ แบบไม่แสดงทุกอัน

SELECT SUM(weight) AS total_weight FROM table_name

SELECT SUM(weight) AS total_weight FROM table_name WHERE id IN (1, 2, 3)

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT SUM(weight) AS total_weight FROM table_name WHERE id IN (1, 2, 3)";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    $row = $result->fetch_assoc();
    echo "Total weight: " . $row["total_weight"];
} else {
    echo "0 results";
}
$conn->close();
?>