如何使用PHP打印表中的所有行？

<?php
// 连接数据库
$servername = "localhost";
$username = "your_username";
$password = "your_password";
$dbname = "your_database";

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 执行查询
$sql = "SELECT * FROM table_name";
$result = $conn->query($sql);

// 遍历结果集并打印行数据
if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo "列1: " . $row["column1"] . ", 列2: " . $row["column2"] . "<br>";
    }
} else {
    echo "表中没有数据";
}

// 关闭数据库连接
$conn->close();
?>