Here is the background management system for your reference, you can use JAVA, Python, PHP, etc. to implement
The background management system is divided into 3 levels of management.
The top is the 1st level menu, and the left side is the 2nd level and 3rd level menu.
When operating, first click on the required 1st level menu at the top
, and then the corresponding 2nd level and 3rd level menus will be displayed on the left side
