使用PDO替代mysql_num_rows

$res = $DB->query('SELECt COUNT(*) FROM table');$num_rows = $res->fetchColumn();

要么

$res = $DB->prepare('SELECt COUNT(*) FROM table');$res->execute();$num_rows = $res->fetchColumn();

您也可以使用它来询问数据是否存在或被选择：

$res = $DB->query('SELECt COUNT(*) FROM table');$data_exists = ($res->fetchColumn() > 0) ? true : false;

或使用您的变量：

$res = $DB->query('SELECt COUNT(*) FROM table');$message = ($res->fetchColumn() > 0) ? array('status' => 'ok') : array('status' => 'error');