PHP -分解关联表的结果查询

<?php
// 假设有两个表：users和orders
// users表包含用户的基本信息，orders表包含用户的订单信息

// 连接数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";
$conn = new mysqli($servername, $username, $password, $dbname);

// 查询用户的订单信息
$sql = "SELECT users.username, orders.order_id, orders.order_date 
        FROM users 
        INNER JOIN orders ON users.user_id = orders.user_id";

$result = $conn->query($sql);

// 分解关联表的结果
$users = array();
while ($row = $result->fetch_assoc()) {
    $username = $row['username'];
    $order_id = $row['order_id'];
    $order_date = $row['order_date'];

    // 将结果按照用户名进行分组
    if (!isset($users[$username])) {
        $users[$username] = array();
    }

    // 将订单信息添加到对应的用户名下
    $users[$username][] = array('order_id' => $order_id, 'order_date' => $order_date);
}

// 打印结果
foreach ($users as $username => $orders) {
    echo "用户名: " . $username . "<br>";
    foreach ($orders as $order) {
        echo "订单ID: " . $order['order_id'] . " 订单日期: " . $order['order_date'] . "<br>";
    }
    echo "<br>";
}

// 关闭数据库连接
$conn->close();
?>