Draw an ER diagarm for the company personnel databas from 12.3. Use that diagram to derice an appropriate set of base relvar definitions.

NOTE : The standard notations of E/R diagram and relational table mapping rules should be followed.

12.3 Fig. 12.19 shows the information to be recorded in a company personnel database, sented as it would be in a hierarchic system such as IMS. The figure is to be understood as follows: The company has a set of departments. " Each department has a set of employees, a set of projects, and a set of offices. " Each employee has a job history (set of jobs the employee has held). " For each such job, the employee also has a salary history (set of salaries received while employed on that job). Each office has a set of phones. DEPARTMENT EMPLOYEE PROJECT OFFICE JOB PHONE SALARY HISTORY Fig. 12.19 A company database (hierarchic view) The database is to contain the following information: For each department: department number (unique), budget, and the department manager's employee number (unique) - For each employee: employee number (unique), current project number, office number, and phone number; also, title of each job the employee has held, plus date and salary for each dis- tinct salary received in that job For each project: project number (unique) and budget For each office: office number (unique), floor area, and phone number (unique) for all phones in that office Design an appropriate set of relvars to represent this information. State any assumptions you make regarding functional dependencies