Order Id

Hi, Im trying to create an order management system. Each order should have a number but this number is consecutive for the department, where the order belongs to.

For example, if the latest order from Human Resources is #8, the new order will be #9. But if the latest order from Production is #20, the new order will be #21.

The idea is that the order number is automatically generated after you select the department.

I appreciate your help so I can achieve this.