php关闭deprecated

// 已弃用的代码
$result = mysql_query("SELECT * FROM users");
while ($row = mysql_fetch_assoc($result)) {
    echo $row['username'];
}

// 使用mysqli的替代方案
$mysqli = new mysqli("localhost", "user", "password", "database");
$result = $mysqli->query("SELECT * FROM users");
while ($row = $result->fetch_assoc()) {
    echo $row['username'];
}

// 或者使用PDO
try {
    $pdo = new PDO("mysql:host=localhost;dbname=database", "user", "password");
    $stmt = $pdo->query("SELECT * FROM users");
    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        echo $row['username'];
    }
} catch (PDOException $e) {
    echo "Error: " . $e->getMessage();
}