在php中显示相关表格中的数据

<?php
// 连接数据库
$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);
}

// 查询数据
$sql = "SELECT * FROM 表名";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出数据
    echo "<table>";
    echo "<tr><th>列1</th><th>列2</th><th>列3</th></tr>";

    while ($row = $result->fetch_assoc()) {
        echo "<tr>";
        echo "<td>" . $row["列1"] . "</td>";
        echo "<td>" . $row["列2"] . "</td>";
        echo "<td>" . $row["列3"] . "</td>";
        echo "</tr>";
    }

    echo "</table>";
} else {
    echo "没有找到相关数据";
}

// 关闭数据库连接
$conn->close();
?>