The source command cannot be used?

<code>You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'source D:\Server\three\public\export.sql' at line 1</code>

<code class="php">
function ImportDB($dbh) {
  $sql = 'source '.realpath('export.sql');
  try {
    $stmt = $dbh->prepare($sql);
    var_dump($stmt->execute());
    var_dump($stmt->errorInfo());
  }
  catch (PDOException $e) {
    print $e->getMessage();
  }
}
</code>