Hi Guys im trying to draw a erd with uml notation according to a case study, but im having difficulties as im a beginner.
1) A department have many employees, although each department must have at least three employees. Every employee works for one and only one department. every department has a manager - only one manager per department. Clearly a manager is an employee of the company, but not all employees are managers.
2) A department may have many machines and every machine is assigned to a specific department.
3) A machine may be reported for maintenance numerous times. maintenance is done on a machine only once on a given day. some machines are so new they many not have required any maintenance yet.
here is what i've drawn so far:
As i think that Zero or more machines can be reported for maintenance and that Zero or more machines are maintained then there is a m:m relationship so we have to resolve it by adding a link entity. but im a bit confused on how to chose the Noun to describe the relation. and to solve it properly.