A company database needs to store information about employees $($SSN$,$ with salary and phone,

identified by SSN$),$ departments $($dno$,$ dname, and budget, identified by dno$),$ and children of

employees $($with name and date of birth$).$ Each employee can work in one and only one

department; a department can have one or more employees. Each department is managed by an

employee; an employee can only manage one department. A child must be identified by name

when the parent $($who is an employee; assume that only one parent works for the company$)$ is

known. We are not interested in information about a child after the parent leaves the company