1. Database Design and Implementation
WELCOME aboard SA0951a
Database Design and Implementation

2. SA0951a Aim/Learning Outcomes
…An extensive experience in designing and implementing advanced database applications.
Outcomes
Critically analyse application requirements and design appropriate conceptual database models.
Demonstrate an understanding of databases using a mainframe DBMS, including database programming techniques.
Evaluate the different approaches to data manipulation using SQL demonstrating one of the options within an application.
July 19

3. Materials and Delivery
All materials are held on the BlackBoard/WebCT site for this module
Check each week to see what’s coming up
Downloads available
Self-assessments, lectorials, labs etc
WebCT has a discussion forum if you would like to “air” something with your classmates (keep it politically correct and academic though!)
July 19

4. Delivery Schedule Lectorials, tutorials, labs all on Friday
Except………..
This week and weeks 6 and 10
In weeks 6 and 10
lecture will be
Lab will be in at 3-5
Tutorials are NOT affected
This is because the deliverers are attending a database workshop in weeks 6 and 10 on fridays!
July 19

5. What are we trying to teach you?
To go through the process of database development from inception to delivery
Conceptual design
Translation to a logical design
Implementing design
Building
Querying
Programming
Testing testing testing!
July 19

6. How are we going to do it?
We encourage and expect interaction in classes
So, don’t just listen, actively engage with us
We’ll make tutorials interactive so you have time to assimilate ideas and practice with colleagues
So some group activity will be encouraged
We expect therefore
Your participation and contributions with your peers
To keep up the pace and develop your own level of enquiry
July 19

7. Assessment ……… is twofold
A paper test in week 13 will examine the early stage of database design issues
This is 40%
A coursework submission & viva in early January (week 17) before term 2 starts will examine the practical issues of querying and programming aspects
This is 60%
The lab work will prepare you for this
July 19

8. Reading & Study
You will learn at different paces but should aim to be up-to-date by the start of the following week
AT the end of each lectorial we shall recommend reading/practice to keep you on track
Aim to spend 10 hours or so each week on the module
July 19

9. We start with Relational Modelling
The relational model is underpinned by mathematical set theory
It arranges data in a database into a set of 2-D logically related TABLES.
Each table contains many attributes
Each attribute contains data
If your relational model is badly designed then you will encounter anomalies
We start therefore by considering how NOT to design a database!
July 19

10. Why is this Single Table design poor?
Student
Age
Sex
Module
Title 1 18 m
SA0951 DB
SA0954 OO 2 25 f 3 33
SA0956
JAVA
we INSERT, MODIFY and DELETE data
And we HATE to duplicate data and/or lose it unintentionally 
So, in groups, consider the effects of the following:
Insert a new student studying SA0951
Delete student 3
Modify the age of student 1
July 19

11. What have you learnt?
That anomalies will occur if you don’t design your data model correctly
What we really need are lists of students and modules in our database like this
But can you see a problem even with this?
What information is lost?
Student
Age
Sex 1 18 m 2 25 f 3 33
Module
Title
SA0951 DB
SA0954 OO
SA0956
JAVA
July 19

12. How do we make the model relational?
The previous example had two UNLINKED tables and therefore we could not model things like students taking many modules
To link them we need to consider KEYS
EVERY table in a relational model has a PRIMARY KEY
A link is formed when a primary key is matched to a FOREIGN KEY in another table
July 19

13. Key definitions Candidate key
A unique identifier for a table (there may be more than one)
The key can be composed of any number of attributes
Primary key (PK)
The chosen candidate key
Foreign key (FK)
A key that matches a primary key
July 19

14. Over to you! Student Module grade 1 SA0951 18 SA0954 14 2 15 3 SA0956
Choose a PRIMARY KEY for this table by considering the candidates. Explain why you chose it.
July 19

15. OK , so now we need to LINK
Think of a link as having a “1” end at the primary key and a “1” or “many” at the foreign key end.
From the example, ask yourself ……….
How many modules could a student take?
How many students could any module have on it?
July 19

16. Here’s the model, what are the PK and FK’s that link the tables together?
Student
Age
Sex 1 18 m 2 25 f 3 33
Module
Title
SA0951 DB
SA0954 OO
SA0956
JAVA
Student
Module
grade 1
SA0951 18
SA0954 14 2 15 3
SA0956 9
Remember you need to identify the PK for each table and then the foreign keys that match a PK.
You have already found the PK for the bottom table.
July 19

17. We are well on the way now ……
We just need a few extra rules now for the keys. We call them integrity constraints
ENTITY integrity
A PK cannot have duplicate or null entries in it
REFERENTIAL integrity
Every FK entry MUST have a matching entry in the related PK
An FK can be entirely null, but not partially null
July 19

18. Lets expand our student model … refresh your memory of the keys first
Age
Sex 1 18 m 2 25 3 33 f
Student
Module
grade 4
SA0951 18 1
SA0954 2 15 3
SA0957 9
Module
Title
SA0951 DB
SA0954 OO VB
SA0956
JAVA
Where are the violations of integrity constraints?
Check each of the null entries as part of the exercise
July 19

19. When we store data ……… We store them as a particular TYPE
TEXT for character data
NUMBER for integer and real numbers
DATE for the calendar
Which of these would you use for the student model attributes?
Justify your choice for each
July 19

20. Final group exercise
We want to model customers paying invoices by instalments
Here are the attributes for the model:
Customer Number, customer name, postcode, invoice number, invoice date, invoice bill amount, date and amount paid for each instalment.
You need to decide on:
The number of tables and their attributes
The PK’s and FK’s in the model
We can continue with this in lab if not finished
July 19

21. Directed Reading
Find the chapter on relational modelling in any database book
Connolly and Begg “Database Solutions”
Connolly and Begg “Database Systems”
Ritchie “Relational database principles”
Rob et al “Database Systems”
Any many many more …….
The internet will have many links to the subject matter too ……….
July 19

22. NEXT lecture & Lab Lecture Is at 1-2pm Thursday 24th in 3004
The remaining lectures will be on fridays 1-2 in 3004 except weeks 6 and 10. Remind you of this later.
NO LECTURES ON MONDAYS now – ok?
The labs:
Start Thursday 24th 3-5 in (also weeks 6 and 10)
Again they will be on fridays 2-4 except weeks 6 and 10.
Tutorials
You should be in a Group
These run and 12-1 on fridays, always.
The room is either or 2021 – CHECK!
July 19