Chapter 7: Problem 8
How would you use a composite attribute to model a phone number.
Short Answer
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Chapter 7: Problem 8
How would you use a composite attribute to model a phone number.
These are the key concepts you need to understand to accurately answer the question.
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Get started for freeConsider an educational institution that has departments and where each department offers courses. Suppose departments are assigned unique identifiers and so deptCode is a key for the department entity type. Courses are identified within a department by a course number; course numbers are unique within a department but not across departments. So, History may have a course numbered 215, and English could have a course numbered 215 too. In order to identify a particular course we need to know the department and we need to know the course number. Illustrate an ERD including department and course entity types. Include attributes for the Department (department code and department name), and for Course (course number, title, and description).
Develop an ERD to be used by a company to manage the orders it receives from its customers. Each customer is identified uniquely by a customer id; include the first name, last name, and address for each customer. The company has several products that it stocks and for which customers place orders. Each product has a unique id, unique name, unit price, and a quantity on hand. At any time a customer may place an order which will involve possibly many products. For each product ordered the database must know the quantity ordered and the unit price at that point in time. If the customer does this through a phone call then an employee is involved in the call and will be responsible for the order from the company side. Some orders are placed via the internet. For each order an order number is generated. For each order the database must keep track of the order number, the date the order was placed and the date by which the customer needs to receive the goods.
Consider the enroll in relationship used in this chapter. Suppose we must allow for a student to repeat a course to improve their grade. Develop an ERD and include typical attributes for student, course, etc. We need to keep a complete history of all course attempts by students.
Draw an ERD involving employees and their dependents where each employee has a unique id number and where dependents of the same employee are numbered starting at 1. It may be rare, but we will allow for dependents of the same employee to have the same name and birthdates. Include typical attributes for an employee, and for a dependent include the birthdate, first and last names.
Consider a requirement having to do with benefits that may be given to employees of a company. Suppose employees work in a department and that each employee may have several dependents (spouse, child). Draw an ERD that includes Department, Employee, and Dependent in your design. Include attributes for your entity types.
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