EMP-DEPT

Problem Definition

• a table of departments
• a table of employees
• a table defining the limits of each salary grade

• a new Class Staff with two subclasses Salaried and Contractor
• a method in Department to total the saleries
• a method in each of Salaried and Contractor to calculate the annual salary
• Object reference - an object reference from staff to dept.

Technical description

So we have to split up the declaration of a type from the implementation (body) of the type. The order of presentation here is the order in which the parts need to be declared. In a realistic system, we would have to use a code management system which would know about these dependencies and would execute the updates to the schema in the correct order.

• Remove the Database if necessary

  Define all the Types

• Define the standard Step-function type This will be used to model the salary grade structure.
• Define the child and children types
• Define the Department type
• Define the Staff Type
• Define Salaried as a sub-type of Staff
• Define Contractor as another subtype

  Define the tables to hold instances

• Define the table for Salgrade
• and the Department table
• Define the table for Staff
• Here we define the Dept Implementation separately

  now Load the tables

• Load the Salgrade table
• Load the Department table
• Load the Staff stable
• This update creates all the department references in the staff table
• Some queries
  • list all Staff
  • list the number, name and annualsal of all staff
  • list salaried staff
  • list the commission for salaried staff, hours for contractors
  • list the salaried staff with their grade
  • list the departments and their total annual wage bills
  • list the number, name, department name and annualsal of all staff

Extensions to the Basic Model

Work to do

• Read and understand the structure of the EMP-DEPT OO implementation
• Develop a complete Class (type) diagram ( perhaps using Rational Rose) of the EMP-DEPT system
• Consider how you would make the following further additions to the system:
  • add a new subtype of staff to hold volunteers who are paid an annual gratuity. Define a new version of annualsal for this type of staff.
  • [done] using the Step Function type, define the salary grade
  • [done] add a member function to Salaried to return the appropriate grade
  • [done] add children to staff, with a variable number of child objects, each defining a name and dob
  • implement the manager association using object reference
  • add a member function to Staff to return their manager's name
  • add a member function to Staff to return their level in the hierarchy ( i.e. the number of managers above them + 1)
  • add a member function to return the age of a member of staff in years
  • add a member function to return the length of service in years

Work for me to do

• some forms and results
• bring rose model and oracle implementation into line
• do something with the children
• add all the emp data
• add integrity constraints