In a company database, you need to store information about employees, departments, and children of employees. For each employee, identified by ssn, you must record years (the number of years that the employee has worked for the company), phone, and photo information. There are two subclasses of employees: contract and regular. Salary is computed by invoking a method that takes years as a parameter; this method has a different implementation for each subclass. Further, for each regular employee, you must record the name and age of every child. The most common queries involving children are similar to \Find the average age of Bob"s children" and \Print the names of all of Bob"s children."

A photo is a large image object and can be stored in one of several image formats (e.g., gif, jpeg). You want to define a display method for image objects; display must be defined differently for each image format. For each department, identified by dno, you must record dname, budget, and workers information. Workers is the set of employees who work in a given department. Typical queries involving workers include, \Find the average salary of all workers (across all departments)."

1. Using extended SQL, design an ORDBMS schema for the company database. Show all type definitions, including method definitions.

2. If you have to store this information in an RDBMS, what is the best possible design?

3. Compare the ORDBMS and RDBMS designs.

4. If you are told that a common request is to display the images of all employees in a given department, how would you use this information for physical database design?

5. If you are told that an employee"s image must be displayed whenever any information about the employee is retrieved, would this affect your schema design?

6. If you are told that a common query is to find all employees who look similar to a given image, and given code that lets you create an index over all images to support retrieval of similar images, what would you do to utilize this code in an ORDBMS?