我有多个类方法，如果抛出异常，每个方法都使用事务和回滚。下面的基本示例。classTaskMapper{private$dblayer;publicfunction__construct(PDO$dblayer){$this->dblayer=$dblayer;}publicfunctionsave(Task$task){try{$this->dblayer->beginTransaction();$stmt=...//query/querieshere$stmt->execute();$stmt2=...//query/querieshere$stmt2->execute();$th