需要帮助从PHP中的SQL连接多个表

<?php
// 假设我们有两个表：users和orders
// users表包含用户的信息，orders表包含订单的信息

// 创建数据库连接
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

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

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

// 使用INNER JOIN连接users和orders表，并查询用户的姓名和订单号
$sql = "SELECT users.name, orders.order_number FROM users INNER JOIN orders ON users.id = orders.user_id";

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

if ($result->num_rows > 0) {
    // 输出每一行数据
    while($row = $result->fetch_assoc()) {
        echo "姓名: " . $row["name"]. " - 订单号: " . $row["order_number"]. "<br>";
    }
} else {
    echo "0 结果";
}

// 关闭数据库连接
$conn->close();
?>