如何使用javascript/jquery从php获取总计

$.ajax({
  url: "get_total.php",
  method: "GET",
  success: function(response) {
    // 处理从PHP返回的数据
    var total = parseFloat(response);
    // 在页面上显示总计
    $("#total").text(total);
  },
  error: function(xhr, status, error) {
    console.log("请求失败：" + error);
  }
});

<?php
// 连接数据库并查询数据
// 假设有一个名为"orders"的表，其中有一个名为"amount"的列存储订单金额
$servername = "数据库服务器地址";
$username = "数据库用户名";
$password = "数据库密码";
$dbname = "数据库名";

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

if ($conn->connect_error) {
  die("数据库连接失败：" . $conn->connect_error);
}

$sql = "SELECT SUM(amount) AS total FROM orders";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
  $row = $result->fetch_assoc();
  $total = $row["total"];
  // 将总计返回给JavaScript
  echo $total;
} else {
  echo "0";
}

$conn->close();
?>