php - How to make relation table in mySQL database in which many employees have supervisor and supervisor have the head of supervisor too? -

i have 4 tables in erd here :

a. employee : idemployee, employee_name. b. position : idposition, position_name. c. accomplishment/ task : idaccomplishment, accomplishment_name, date_accomplishment, place_accomplishment. d. assesment (assiciation table between employee , accomplishment tables). 

i want make relation in many employees have supervisor, , many supervisor have head of supervisor. then, employee has accomplishment , must entry accomplishment , own accomplisment score accomplishment table. , supervisor , head of supervisor assess accomplishment employee score accomplishment table too.

this illustration of them, please me make right relation. thankyou