I would like to create a class diagram for a database to represent managers from around the world
Each manager is characterized by name, surname, date of birth, one
or more certificates (A,B,C,D), a series of skills (teamwork, determined, etc.).
a manager has a career during which he can work in several companies. Participation in one
company is characterized by one or more periods of time in which the manager was in that company. Everything is fine
period of time has a start date and an end date. During the manager’s participation in the company, yes
takes into account the number of days worked, the number of finished projects, and the number of undelivered projects (applicable
only to managers who have certified B). The manager can also win individual or corporate prizes.
. Companies are specific by their name and nationality.
prizes can be won once every year. the individual award was awarded to one person per year while by team it means that multiple managers may have won in the same year. Furthermore, the manager can work simultaneously in public and private companies, but never in two private or two public companies at the same time.
note: the relationship between manager and prizes, I had thought of putting a time association class, with year attribute. While project_x is optional.

enter image description here
enter image description here

I tried these two ways but they don’t convince me, I would like to represent the job as a historicized entity containing the total information of when a manager worked in a company and associate it with multiple periods.
for the prizes I have doubts about the multiplicity of the association because the individual prize can be awarded each year to a single manager while the team prize can be awarded to multiple managers. the other doubt was the fact that a manager can work simultaneously for two different types of companies.