php pdo :更新+插入，然后选择返回null

// 连接数据库
$dsn = "mysql:host=localhost;dbname=mydatabase";
$username = "username";
$password = "password";
$dbh = new PDO($dsn, $username, $password);

// 更新操作
$sql = "UPDATE users SET name = :name WHERE id = :id";
$stmt = $dbh->prepare($sql);
$stmt->bindParam(':name', $name);
$stmt->bindParam(':id', $id);
$name = "John Doe";
$id = 1;
$stmt->execute();

// 插入操作
$sql = "INSERT INTO users (name, email) VALUES (:name, :email)";
$stmt = $dbh->prepare($sql);
$stmt->bindParam(':name', $name);
$stmt->bindParam(':email', $email);
$name = "Jane Smith";
$email = "jane@example.com";
$stmt->execute();

// 选择返回null
// 如果更新或插入操作成功，execute方法会返回true，否则返回false。如果你选择返回null，可以使用以下代码：
$result = $stmt->execute();
if ($result) {
    $response = null;
} else {
    $response = "更新或插入操作失败";
}

// 关闭数据库连接
$dbh = null;