$user = "_next4";
$password1 = "kmnoh-456";
$opt = [
	PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
	PDO::ATTR_EMULATE_PREPARES   => false,
	PDO::MYSQL_ATTR_MULTI_STATEMENTS => false,
	PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
	PDO::ATTR_STRINGIFY_FETCHES  => false, // PHP8.1以降の推奨設定
];

try {
	$dbh = new PDO(
		'mysql:host=mysql018.phy.heteml.lan;dbname=_next4;charset=utf8mb4',
		$user,
		$password1,
		$opt
	);
} catch (PDOException $e) {
	// 本番環境ではエラー詳細を外部に露出しない
	error_log($e->getMessage());
	throw new RuntimeException('データベース接続に失敗しました。', 0, $e);
}
	
	  <br />
<b>Notice</b>:  Undefined variable: dbh in <b>/home/users/2/nomachi-sahara/web/nomachi8/a-nomachi.php</b> on line <b>6</b><br />
<br />
<b>Fatal error</b>:  Uncaught Error: Call to a member function query() on null in /home/users/2/nomachi-sahara/web/nomachi8/a-nomachi.php:6
Stack trace:
#0 {main}
  thrown in <b>/home/users/2/nomachi-sahara/web/nomachi8/a-nomachi.php</b> on line <b>6</b><br />