Introduction to Database Systems Exam Preparation

2 Organization of Lecture Notes Group 1 - SQL –L1 – Introduction –L2 – Relational Model –L3 – SQL –I –L4 – SQL –II –L5 – SQL – III –L6- Data Definition & Integrity Constraints – Create Table etc –L7 – Access Control & Views –Additional lecture notes on writing SQL select queries Group 2 – Database Design –L8 – Database Design: ER Modelling –L9 – Database Design: ER Modelling (Continued) –L10 & 11 – Database Design: Normalization Group 3 – Database Connectivity –L12 – Database Programming – JDBC –L13 – Introduction to Web-based DBMS Technology –L14 – Web-based Database Programming with PHP Group 4 – Database Internals –L15 – Database Security –L16 – Transaction Management –L17 – Query Processing –L18 – File Organization & Indexing –L22 – B+-Trees Group 5 – Systems/Applications –L19 – MySQL –L20 – Spatial Databases

3 Exam Structure Answer 3 out of 4 questions in 2 hours but you MUST answer Question 1. –Q1: Database Design or SQL –Q2: Database Design or SQL –Q3: Other –Q4: Other ‘Other’ could mean anything else in the course –DBMS internals, Database connectivity (JDBC, PHP) and Spatial databases Your strategy should be to –Take 5-10 minutes to look over the whole paper first –Then, aim for about 35 minutes per question

4 Question Structure The questions aim to test your knowledge and understanding Each question (25 marks) will be divided approximately into 3 levels: –Bookwork: (3-6) – “knowledge” - what all of you should know! –Seen: (10) – “understanding” - can you solve a problem you've seen ? –Unseen: (9-12) – “knowledge & understanding” – solving an unseen problem For a “pass”, you'll need to get about 12/25... For a “first”, you'll need to get about 20/25 or more.

5 Marking Strategy(1) You can exploit the way examiners mark papers... Most examiners “work towards the middle”: –We try to give marks for poor answers –We try to take away marks from good answers –Intermediate answers are hardest to mark

6 Marking Strategy(2) Your strategy should be to make the examiners work as hard as possible: –Always attempt every part of your chosen 3 questions –Record all the known facts and try to derive any new facts Required solution could be among the derived facts –If you have time at the end, go back and check your answers

7 Student FAQs Will there be any essay-type questions ? –No - but some answers may need a short paragraph Will there be a question on topic X ? –Maybe Will there be any PHP/Java/JDBC programming questions ? –No, but you should be prepared to answer general questions on any of these areas

8 Student FAQs Do I need to memorise all those SQL statements ? You should know how to use common statements, especially SELECT DML (SELECT, INSERT, DELETE, UPDATE) DDL (CREATE, ALTER, DROP) DCL (GRANT, REVOKE) Should be able to say what most other statements do... For a “pass” you just need to learn SELECT statements in all its forms For a “first” you should learn the syntax of all the SQL statements

9 More FAQs Will we have to draw any diagrams ? –Probably - you will not be required to draw complex figures, but you might be asked for a sketch to illustrate your answer... Do we need to read more about Spatial Databases ? –No - The lecture notes should be enough. –Same thing for MySQL and B+Trees Can we get solutions for past papers ? –No - we never give out exam paper solutions: the main reason is we sometimes want to re-use questions!!

10 Example “Database Design” Questions What are ‘Integrity Constraints’? What role do they play in a DBMS? (5) Explain the advantages of using database systems in place of file systems.(3) Explain the differences between the notions of DataBase (DB), DataBase Management System (DBMS) and DataBase System (DBS). (2)

11 Example “Database Design” Questions What is meant by second normal form (2NF)? Examine the following table to check if it is in 2NF. If yes, explain your answer. Else convert the table into 2NF. (5) Staff No Branch No branchAddressnamepositionhoursPer Week S4555B2City Center Plaza, Seattle, WA EllenAssistant16 S3209B416 – 14th Avenue, Seattle, WA EllenAssistant9 S0912B2City Center Plaza, Seattle, WA Dave Sinclair Assistant14 S8743B416 – 14th Avenue, Seattle, WA Dave Sinclair Assistant10

12 Example “SQL” Questions Video ID TitleCopyri ghtYea r RatingRent Per Day LengthForma t Category ID 1Under Siege £ minNTSC3 2Batman2001PG£ minPAL7 3A Few Good men £ minNTSC8 Using only the Videos table, write an SQL query to show the oldest video (oldest video is the one with the earliest copyright year). (5)

13 Example “SQL” Questions In SQL, give one example of each of the following types of statements statements (use the Videos table if you need to refer to a table in your answer): –A Data Manipulation Language (DML) statement (1) –A Data Definition Language (DDL) statement (1) –A Data Control Language (DCL) statement (1) Transactions in a multi-user relational database system sometimes enter into a deadlock. Describe when a deadlock might occur and explain how deadlocks are usually detected and resolved.(5)

14 Example “Other” Questions What are the different types of queries that spatial databases support? Describe one index scheme you will use to enhance the performance of spatial queries. (4) What does the abbreviation ‘BLOB’ stand for? In the context of web-based database applications, give examples of three types of BLOB data. (4) With the help of a sketch, explain the various stages in which a request for a php file that contains MySQL queries is processed by a web server.(4)

15 Example “Other” Questions What is the ‘Lost Update’ problem? Explain how locks can prevent this problem occuring in a multi-user database environment. (4) In relational databases, what is an index? With the help of the Customers table explain how indexing works. (5) The acronym “ACID” represents four fundamental requirements for database transactions. What does “ACID” stand for, and briefly describe the four requirements it represents?(4)