Do not turn over until you are told to do so by the invigilator. Module Contact: Dr. Beatriz de la Iglesia (CMP)

Transcription

1 UNIVERSITY OF EAST ANGLIA School of Computing Sciences January PG Examination DATABASE MANIPULATION CMPSMB11 Time allowed: 3 hours Answer THREE questions. All questions carry equal weight. Notes are not permitted in this examination Do not turn over until you are told to do so by the invigilator. CMPSMB11 Module Contact: Dr. Beatriz de la Iglesia (CMP) Copyright of the University of East Anglia Version 1

2 Page 2 1) (a) Describe at least 4 differences between the file-based approach to data management and the database approach. (b) Describe the ANSI SPARC database model and discuss why such a model is important in the context of Database Management Systems (DBMSs). (c) Explain why a Database Management System may provide the following advantages: i) Improved data integrity, ii) Improved security, iii) Increased productivity. 2) (a) In the context of the Relational Model, describe the following concepts: i) Primary key, ii) Entity integrity, iii) Referential integrity, iv) Domain integrity. (b) The following two relations represent a database containing information about customers and orders; customer (customerno, fistname, lastname, phone ) orders (orderno, customerno*, orderdate) Primary keys are underlined and foreign keys are marked by *. Explain what actions a DBMS might carry out when a customer tuple is updated or deleted. What actions should a DBMS perform when a tuple is inserted into the orders relation?

3 Page 3 (c) Are the above relations in 3 rd Normal Form (3NF) and also in Boyce-Codd Normal Form (BCNF)? Explain the tests that you would perform to establish each level of normalization. 3) A University has a booking system for its rooms. The system contains a relational database with information on events, organisers, rooms and room bookings. The tables are: event (eventid, type, duration) organiser (organiserid, firstname, lastname, ) room (roomid, capacity, projector, whiteboard) booking (eventid*, organiserid*,roomid*, bookingdate, bookingstarttime) where eventid is the unique event identifier; type is either Lec (for Lecture), Sem (for Seminar) or Lab (for Laboratory); duration is the event planned duration given in whole hours; the maximum duration is 4 hours; organiserid is the unique identifier for the event organiser, i.e. a lecturer; firstname, lastname and record details of the organiser; roomid is the unique room identifier; capacity specifies the maximum number the room can accommodate; projector/whiteboard are Booleans specifying whether the room has the said facilities; bookingdate/bookingstarttime are the required date/time for the booking. Events can only start on the hour, thus eventstarttime is an integer variable representing the hour the booking commences using the 24-hour format. A given event can have a number of bookings on different dates. It is assumed, however, that the same event is not booked more than once per day. An organizer can be associated with any number of bookings. A room may also be associated with a number of bookings. PLEASE TURN OVER

4 Page 4 (a) Produce a simple Entity-Relationship diagram for the above set of tables. You only need to include entities and relationships with the cardinality and optionality, but not attributes. Include any assumptions that you will need to make to decide on the optionality of relationships. (b) Write the following SQL queries: (i) Produce a list of eventids for all events booked on or after 12:00 on the 17 th January [4 marks] (ii) Produce a list of organisers, including all details, for those that have bookings on the 1 st February [6 marks] (iii) List chronologically all event details for events booked for an organizer with an organiserid of 100, along with the dates and times of the associated bookings. (iv) List all events for which there are no corresponding bookings. [6 marks] (v) List rooms which are not booked on the 19 th January 2014 between 9:00 and 11:00 and have both a projector and a whiteboard. 4) (a) In the context of the database design methodology, describe the following phases: i) Conceptual database design, ii) Logical database design, iii) Physical database design. (b) A University has different types of people associated with it. For all associated members of the University details such as Title, Name, Surname, and contact details must be kept. Students have a major subject that they are studying. Graduate students have a thesis title and undergraduate students have a number of contact hours. On the other hand, employees of the University all

5 Page 5 have a hire-date. Employees working in administration have a job title whereas lecturers have a rank and subject. Depict this scenario using Enhanced Entity Relationship (EER) Modelling. Create a diagram including participation and disjoint/overlapping constraints. Specify the assumptions you will need to make to support the constraints. (c) Why are the enhanced aspects of EER modelling necessary? What kind of applications may require the enhanced semantic concepts available in EER modelling? 5) (a) The consistency and reliability aspects of transactions are due to the ACID properties of transactions. Discuss these properties and how they relate to the concurrency and recovery mechanisms. (b) Briefly discuss the statements available in SQL for implementing the transaction mechanism. (c) Describe, with examples if necessary, the types of problem that can occur in a multi-user environment when concurrent access to the database is allowed. END OF PAPER