您正试图访问数组中的指标没有设定。这引发了一个通知。

You're attempting to access indicies within an array which are not set. This raises a notice.

你现在很可能会注意到它，因为你的代码已经转移到php.ini有 error_reporting的服务器设置为包含 E_NOTICE 。通过将error_reporting设置为 E_ALL&来抑制通知。 ~E_NOTICE （不推荐），或在您尝试访问索引之前验证索引是否存在：

Mostly likely you're noticing it now because your code has moved to a server where php.ini has error_reporting set to include E_NOTICE. Either suppress notices by setting error_reporting to E_ALL & ~E_NOTICE (not recommended), or verify that the index exists before you attempt to access it:

$month = array_key_exists('month', $_POST) ? $_POST['month'] : null;