The table below lists customer/car hire data. Each customer may hire cars from various outlets throughout Glasgow. A car is registered at a particular outlet and can be hired out to a customer on a given date.

Question


(a) The data in the table is susceptible to update anomalies. Provide examples of how insertion, deletion, and modification anomalies could occur on this table.
(b) Identify the functional dependencies represented by the data shown in the table. State any assumptions you make about the data.
(c) Using the functional dependencies identified in part (b), describe and illustrate the process of normalization by converting Table 1 to Third Normal Form (3NF) relations. Identify the primary and foreign keys in your 3NF relations.

Answer 1

(a) Using the data shown in the table above, the student should provide examples of how insertion, deletion, and update anomalies could occur.
(b) For answer see figure below.
(c) For answer see figure below.


The primary key of the original relation is appointment number (appNo) and the relation is
already in 2NF. The original relation also has two alternate keys instructorID, dateTime and
clientID, dateTime. The functional dependencies fd2 to fd5 represent transitive dependencies
in the original relation and must be removed to create the following relations in 3NF.
Appointment (appNo, dateTime, instructorID, clientID)
Primary Key appNo
Alternate Key dateTime, instructorID
Alternate Key dateTime, clientID
Foreign Key instructorID references Instructor (instructorID)
Foreign Key clientID references Client (clientID)
Instructor (instructorID, iFName, iLName)
Primary Key instructorID
Client (clientID, cFName, cLName, cAddress)
Primary Key clientID