Relational databases: theory and practice Assignment

ANSWER ALL QUESTIONS

Question 1 - Use the block notes to answer the following questions:

i. Explain what is meant by the process of denormalization and how it is done.

ii. Explain why we may need to use denormalization (i.e. provide the motivation for denormalization)

iii. Explain when it is  a good idea to use normalization.

iv. Give an example of denormalization.

v. Explain the drawbacks of denormalization.

vi. Explain when denormalization should be avoided.

Question 2 - Use the e-library and other resources to answer the following questions:

i. Explain what is meant by extensible relational database design.

ii. Explain what is meant by the "Entity-Attribute-Value (EAV)" approach.

iii. Explain how can the EAV approach be used to implement database extensibility.

iv. Give an example of using the EAV approach to implement a simple relational database with extensibility features.

v. Explain why we may need to use the EAV approach to implement relational database extensibility (i.e. describe the advantages of the EAV approach for implementing relational database extensibility).

vi. Explain why we may not sometimes wish to use the EAV approach to implement relational database extensibility (i.e. describe the disadvantages of using the EAV approach for implementing relational database extensibility).

You must provide at least two references in the Harvard style of referencing, excluding your course materials and Wikipedia.  At least one of the references should be a recent reference (within the last four years).

Question 3 - Develop a conceptual model for the following scenario.  The data model should consist of the usual 5 components: E-R diagram, Entity Types (including entity type identifiers), assumptions, additional constraints, and limitations:

It is desired to develop an online pizza ordering database for a pizza shop.

For each customer, we need to keep a customer id, first name, middle name, last name, title, telephone number and address.

A customer may make zero or more orders.  For each order, we maintain a unique order id, a date, a time, and any special discounts offered on the whole order.

Each order is made by exactly one customer, taken by exactly one employee, delivered by exactly one driver and consists of one or more line-items.

An order cannot contain more than 100 line items.

For each employee, we keep an employee id, a first name, a middle name, a last name, an address, a telephone number and a salary.

An employee can take many orders.

For each driver, we keep the driver id, name, telephone number and hourly salary.

A driver may deliver many orders.

For each Line item, we keep a line number, a quantity, and a sale price.

A line item must be associated with a single order and must also be associated with a single menu item.

A menu item is a main item that can be ordered by itself from the menu.  There are two types of menu items: standard items, like standard specialty pizzas, French fries, salads, drinks, etc. and custom pizzas which you can customize yourself by choosing the crust type, the toppings, and so on.

For each menu item, we keep a menu number, a name, a description, a menu price, and customer special requests.

A menu item can participate in zero or many line items.  Every menu item must be either a standard item or a custom pizza but not both.

For standard items, we keep the menu number, which indicates that the menu item having this menu number is a standard item and the portion size (small, medium or large).

Obviously, a standard item must be associated with a single menu item.

For custom pizzas, we keep pizza-diameter, type of crust and flavor of crust.

A custom pizza must also be associated with a single menu item and can have many toppings up to a maximum of 7 toppings.

For each topping, we keep a type, pizza-diameter and price.  A custom pizza can only be supplied with a topping priced for the same diameter.

A toping may be used by many custom pizzas.

Note: you should expect about 10 entity types, 9 relationship types, 45 attributes, 8 additional constraints, 4 assumptions and 2 limitations in the CDM for this application.

Question 4 -

i. Convert the following relational representation back into a CDM using three relationships and four entity types.  Include the ER diagram, the entity types and the additional constraint sections only.

ii. Consider the schema below to answer the following questions:

R (A, B, C, D, E, F, G)

fd1: (A, B) → C, D, E, F, G

fd2: C → A, B, D, E, F, G

fd3: D → E

fd4: F → G

a. Show that relation R is in 2NF and not in 3NF explaining why.

b. Normalize the relation R into a set of 3NF relations. Show the primary keys.

c. Further normalize the results of the previous step into a set of BCNF relations if not already in BCNF and show the primary keys.

Question 5 - You will need to refer to the University database to answer this question. Write SQL queries to perform the following operations. In each case show the SQL statement you used and the actual output from your DBMS.  You are required to show the actual output of your queries.

a) List patient details for all male patients in ward number 'w5'.

b) List the ward numbers of all occupied wards with no duplicates.

c) List the patient ids, the start date and reason for treatment for all patients undergoing a treatment for a reason that contains the word 'temperature' or the word 'fever' and who started their treatment after 5 December 2006.

d) List the names of all specialists along with their specialisms.

e) Get the ward numbers and ward names for all wards that have no patients.

f) Write a query to get the number of distinct patients undergoing each type of treatment (i.e. reason for treatment) in the database, ordered alphabetically by the reason for the treatment.

g) Write a query to get the names of all patients receiving a prescription whose daily dosage is higher than the average daily dosage of all prescriptions using the same drug.

h) Write a query to retrieve the ward number and average weight of patients for all wards having more than three patients, excluding ward w5.

Attachment:- Assignment.rar