php留言板成品

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>留言板</title>
</head>
<body>
    <h1>留言板</h1>
    <form action="submit.php" method="post">
        <textarea name="message" required></textarea><br>
        <input type="submit" value="提交">
    </form>
    <?php
    $conn = new mysqli("localhost", "username", "password", "database");
    if ($conn->connect_error) {
        die("连接失败: " . $conn->connect_error);
    }
    $sql = "SELECT * FROM messages";
    $result = $conn->query($sql);
    if ($result->num_rows > 0) {
        while($row = $result->fetch_assoc()) {
            echo "<p>" . $row["message"] . "</p>";
        }
    }
    $conn->close();
    ?>
</body>
</html>

<?php
$conn = new mysqli("localhost", "username", "password", "database");
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}
$message = $_POST['message'];
$sql = "INSERT INTO messages (message) VALUES ('$message')";
if ($conn->query($sql) === TRUE) {
    echo "留言已成功提交";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
?>