SUMMER EXAMINATIONS 2014

Transcription

1 SUMMER EXAMINATIONS 2014 MODULE TITLE LEVEL TIME ALLOWED Database Architecture Four Two hours Instructions to students: Enter your student number not your name on all answer booklets. The exam is split into two sections: SECTION A Compulsory Case Study Question SECTION B - Answer two questions out of three. Weighting 50% each section. Answer each question in a separate answer booklet. Use of a non-programmable calculator is permitted. No. of Pages 5 No. of Questions 4 Page 1 of 5

2 SECTION A - Compulsory Case Study Question Dancing Queen Party Hire is a small company that sells dresses, suits and accessories for adults and students balls. They have been trading for 8 years and are steadily growing in success. The company has a dedicated Sales team, which they intend to extend in the future. Details of Sales staff are recorded for salaries etc. The company sell a number of different outfits and accessories and therefore has relationships with many different suppliers such as Fun Frocks and Smart Suits etc. They store all the contact details for the suppliers as well as the details of the products. Each supplier provides a number of different products to suit a variety of customers and pockets; from full ball gowns to simple suits. They also sell accessories like tiaras and bow ties. Each product has details that are recorded on the system, these include a product number, name, description and price. Dancing Queen was set up around some time ago but now has quite a number of customers on the system. Customer details such as name, address and are stored. Many customers are party dress mad and have placed several orders over the years and are valued customers. All orders are recorded and stored. Each order has a unique number and an order date as well as a total cost. Orders often include a number of items, including accessories like necklaces and earings. Each order is associated to an individual from the sales team. All orders must be signed off by a sales employee who is responsible for the order. Dancing Queen has decided to change their systems and have asked you, as a database architect to design the new database back end. Question 1 a. You are required to identify the entities from the scenario and produce an entity relationship model. State clearly any assumption you make and resolve any many to many and one to one relationships. (20 marks) b. For each entity in your model describe the table specification. Include primary keys, foreign keys and other attributes. (15 marks) Page 2 of 5

3 c. Define the following terms. Use examples from your model in questions a. and b. to support your explanation. i. Entity integrity ii. Referential integrity iii. Domain integrity (Total: 50 marks) END SECTION A SECTION B FOLLOWS OVERLEAF Page 3 of 5

4 SECTION B Answer TWO questions out of three. Question 2 a. Normalise the following document to third normal form (3NF). Show clearly all stages that are involved (ie UNF, 1NF, 2NF and 3NF). (20 marks) EXAM SCHEDULE Examiner No: E007 Examiner Contact: JONES Examiner Name: Mr Smith exam No day Start time Student student_name E1 12 Jun St1 Melinda St2 Carmel E2 19 June St1 Melinda St3 Bob E3 26 June St1 Melinda St2 Carmel b. Develop the entity relationship diagram from the entities identified above. The diagram should be drawn using standard notation. (Total: 25 marks) Question 3 Discuss the concept of database normalisation and its central semantic concept; functional dependency. (25 marks) Page 4 of 5

5 Question 4 Below is an extract from an entity relationship model together with attribute list. A skeleton interview table is provided with keys, required defaults and constraints. POSITION APPLICANT INTERVIEW Tables: position (position_code, title, description, level) applicant (applicant_code, first_name, surname, DOB, profile, contact) interview (*position_code, * applicant_id, interview_date, status) interview Table Attributes Keys Constraints/Defaults position_id PK app_id PK date status DEFAULT pending Primary Key * Foreign Key Write the SQL commands to execute the following: a. Create the interview table with appropriate datatypes (10 marks) b. Use the ALTER command to set the primary key (4 marks) c. Use the ALTER command to set the foreign keys (6 marks) d. You run an SQL insert statement into the interview table which resulted in the following error message: ERROR at line 1: ORA-00291: integrity constrain (fk_i_position_id) violated parent key not found Assuming the SQL syntax was correct; explain what you understand by this error message using a diagram to illustrate your answer if appropriate. (Total: 25 marks) END OF SECTION B END OF PAPER Page 5 of 5