mysql 다음 인덱스 값 뽑기

$sql = "SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'dbname-homes-omachine' AND TABLE_NAME = 'COMMENTSTBL'";

$stmt = $pdo->query($sql);

$resultMaxIdx = $stmt->fetch(PDO::FETCH_NUM);

var_dump($stmt);

var_dump($resultMaxIdx);

$cmtOriginId = $resultMaxIdx[0];

echo "<br />";

echo $cmtOriginId;