当没有找到记录时，PDOStatement :: fetch（）或fetchAll（）方法会返回什么？ （PHP + MySQL）

$dbh = new PDO($dsn, $username, $password);
$stmt = $dbh->query($query);
$array = $stmt->fetch();
$stmt->closeCursor();

What would fetch() or fetchAll() method return when no records were found?

• An empty array?
• A non-empty array with field names as the keys and NULLs as the values?
• A NULL value?
• A FALSE value?
• Or just to trigger an error?

The answer is a FALSE, after I tested it myself.