Tutorial / Laboratory Sheet

1.Define each of the following terms:

a.entity type

b.entity instance

c.Attribute

d.Relationship type

e.Identifier

f.Multivalued attribute

g.Cardinality constraint

h.Weak entity

i. Derived attribute

2.State four criteria for selecting identifiers for entities

Case Study

TOURS ARE US

Brothers, Richard and Allan Winston, operate Tours Are Us. The business specializes in unusual tours for adventurous people who want something different from the general tourist destinations and activities. The business has been operating very successfully for the past three years. Growth in the second and third years was about 25%.

Allan and Richard have been identifying current, manual, tour booking procedures. They would expect the new database management system to allow users to operate in much the same way as they are now. In other words, they expect the system to support user activities and tasks.

Currently, when a client comes in or phones to book a tour, the attendant first checks the card system to determine whether this client's details have been recorded and whether these are still accurate. if this is a new client, then the following details must be recorded before any tour can be booked:

Client's name, address and contact number, and preferred payment method; ie cash, cheque or credit card.

Once these details have been recorded, a tour booking can be made. The client must put a deposit on the tour (or pay in full) on the day that the booking is made. Tour prices are given on a per person basis and cover all travel, accommodation and meal expenses. Thus the client must also indicate how many people are going on this tour. Payment for tours must be finalised 10 days before the tour's departure date. Tours can have different prices depending on what time of year they are being offered. Most of the tours are offered more than once a year.

For each tour, information is also listed about the city from which the tour departs and departure time. It is up to the client to make their way to the departure location.

When the booking is completed, the client is given a tour itinerary that lists the various destinations on the tour. In addition, it also lists:

the name and rating (ie 1-5 star) of the accommodation at each destination

the duration of stay in days at a particular destination

some of the main features at the destination.

The above is the basic information that needs to be stored in the new database management system. Richard and Allan will hire someone to transfer the information currently stored on their card system to the database management system once it is operational. They also need to be assured that the new system will have sufficient flexibility to be extended in the future if the need arises

Exercise: Construct an ER model using the information in the TOURS R US case study below.