PDO MYSQL Create table (如果不存在)并查看它是否已创建

$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";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "数据库连接成功";
} catch(PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
}

$sql = "CREATE TABLE IF NOT EXISTS users (
    id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(30) NOT NULL,
    email VARCHAR(50) NOT NULL,
    password VARCHAR(255) NOT NULL
)";

try {
    $conn->exec($sql);
    echo "表创建成功";
} catch(PDOException $e) {
    echo "表创建失败: " . $e->getMessage();
}

$sql = "SHOW TABLES LIKE 'users'";

$result = $conn->query($sql);
if ($result->rowCount() > 0) {
    echo "表已创建";
} else {
    echo "表未创建";
}