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Chapter 7: Problem 7

In some large organizations where there are several buildings and floors we see room numbers that encode information about the building, floor, and room number. For example in case the room 3C13 stands for room 13 on the third floor of the Centennial building. Suppose we need to include Room in an ERD. How would you represent the room number given that you must include atomic attributes only?

Short Answer

Expert verified
The atomic attributes for the 'Room' entity in the ERD would be 'Building', 'Floor', and 'Room Number'. Each room can be uniquely identified by these three attributes.

Step by step solution

01

Understand Atomicity

Atomicity in database terms means that data cannot be further divided. Now consider the room number attribute '3C13'. It's made up of three separate pieces of information, the room number '13', the floor number '3', and the building 'C'. To maintain atomicity, these should be split into three separate attributes.
02

Break Down the Room Number

Separate the room number '3C13' to 'Building C', 'Floor 3', and 'Room 13'. Each of these is now an atomic attribute.
03

Create Entity and Attributes

Create an entity called 'Room' with three attributes. These attributes are 'Building', 'Floor', and 'Room Number'.
04

Diagram the ERD

Each room should be uniquely identified by its floor, building, and room number. 'Room Number' can be the primary key including 'Building' and 'Floor'.

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Most popular questions from this chapter

A birthdate attribute would appear for many entity types – for example students, employees, children. What is a birthdate likely to be: key or non- key?

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.

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