如何计算不同阶数的平均值mysqli

<?php
// 连接到MySQL数据库
$conn = mysqli_connect("localhost", "username", "password", "database");

// 检查连接是否成功
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}

// 构建查询语句
$query = "SELECT order_amount FROM orders";

// 执行查询
$result = mysqli_query($conn, $query);

// 初始化变量
$sum = 0;
$count = 0;
$averages = array();

// 处理查询结果
while ($row = mysqli_fetch_array($result)) {
    $sum += $row['order_amount'];
    $count++;

    // 计算不同阶数的平均值
    $average = $sum / $count;
    $averages[$count] = $average;
}

// 显示结果
foreach ($averages as $order => $average) {
    echo "阶数 " . $order . " 的平均值为: " . $average . "<br>";
}

// 关闭数据库连接
mysqli_close($conn);
?>