Consider the following schema:

Employee$($Ename $,$ SSN$,$ Bdate, City $,$ Dnumber$)$

Department $($ Dname,Dno,Dmgr$\_$SSN$)$

Project$($Pname$,$ Pnumber, Plocation, Dnum$)$

WorksON$($SSN$,$Pnumber,Hours$)$