An Employee has properties of
empno, ename, sal (amount), possibly comm (amount) and hiredate.
An Employee is identified by its empno.
sal
A Department has properties of deptno, dname and location. A Department is identified by its deptno. A Department, in the role of deptno , may employs many Employees.
A SalGrade has properties of
grade, losal (amount) and hisal (amount).
A SalGrade is identified by its grade.
A SalGrade may
be had by many Employees.