Transcript Review and Assignment 2

44220: Database Design & Implementation
Review & Assignment 2
Ian Perry
Room: C41C Tel Ext.: 7287
E-mail: [email protected]
http://itsy.co.uk/ac/0708/sem2/44220_DDI/
Data, Information, …
Ian Perry
44220: Database Design & Implementation: Review & Assignment 2
Slide 2
The ‘Data Modelling Stack’
Conceptual Overview of things
Logical
Physical
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that are perceived to
be of ‘interest’ in the
‘real’ world.
Data elements & the
relationships between
those elements in a
tabular form.
Actual data held in a
database & the
means to manipulate
that data.
Model of the
Business System.
(ER Model)
Model of Data
Storage Theory
(Db Schema)
Physical
Implementation
(RDBMS)
44220: Database Design & Implementation: Review & Assignment 2
Slide 3
Conceptual Model - ER Diagram
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Staff, Student, Course (SSC)
Team
M
1
<= taught by
M
<= part of
Indicates
Mandatory
Participation
Course
1
Pay
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1
<= paid at
applies to =>
M
Staff
1
tutor for => M
<= tutored by
44220: Database Design & Implementation: Review & Assignment 2
Student
Slide 4
Logical Model – Schema & Domains
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Schema: SSC
Domains:
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StudentIdentifiers: Number, from 1 to 9999
Titles: Text, >=2 & <= 4 Characters, First Char Caps, e.g. Mr,
Ms, Mrs, Miss, Prof, Dr.
PersonNames: Text, <= 12 Characters, First Char Caps.
OPoints: Number, from 0 to 100.
StaffIdentifiers: Number, from 1001 to 1199.
SPoints: Number, from 1 to 6.
StaffBirthDates: Date, dd/mm/yyyy, >= 21 years before
today.
PayRates: Money, from £15,000 to £20,000, in £1,000
increments.
CourseIdentifiers: Number, from 101 to 110.
CourseNames: Text, <= 15 Characters, First Char Caps.
CourseDurations: Number, 3, 6, 9 or 12 (Months).
44220: Database Design & Implementation: Review & Assignment 2
Slide 5
Logical Model – Relations 1
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Relation: Student
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EnrolNo: StudentIdentifiers
Title: Titles
FirstName: PersonNames
SurName: PersonNames
OLevelPoints: OPoints
Tutor: StaffIdentifiers
Primary Key: EnrolNo
Foreign Key: Tutor references Staff.StaffID
Relation: Staff
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StaffID: StaffIdentifiers
Title: Titles
FirstName: PersonNames
FamilyName: PersonNames
ScalePoint: SPoints
DOB: StaffBirthDates
Primary Key: StaffID
Foreign Key: ScalePoint references Pay.ScalePoint
44220: Database Design & Implementation: Review & Assignment 2
Slide 6
Logical Model – Relations 2
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Relation: Pay
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Relation: Team
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ScalePoint: SPoints
RateOfPay: PayRates
Primary Key: ScalePoint
CourseCode: CourseIdentifiers
StaffID: StaffNumbers
Primary Key: CourseCode & StaffD
Foreign Key: CourseCode references Course.CourseCode
Foreign Key: StaffID references Staff.StaffID
Relation: Course
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CourseCode: CourseIdentifiers
Name: CourseNames
Duration: CourseDurations
Primary Key: CourseCode
44220: Database Design & Implementation: Review & Assignment 2
Slide 7
What is a Physical Data Model?
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The Physical Implementation (hardware &
software) of a Logical Data Model:
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Physical Data Model must enable:
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it is useless to progress to this stage of database
development if your Logical Data Model is NOT
demonstrably ‘robust’.
data to be stored (& maintained) in structured
manner.
retrieval of specific groupings of data
(information?).
There may be several constraints:
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depending upon the software application chosen.
44220: Database Design & Implementation: Review & Assignment 2
Slide 8
Logical => Physical
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i.e. translate a ‘logical’ Database Schema
into a ‘physical’ Database:
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Schema
Relations
Attributes
Domains
Key Fields
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=>
=>
=>
=>
=>
Database
Tables
Field Names
Data Type
Field Size
Input Mask
Validation Rule
Relationships
44220: Database Design & Implementation: Review & Assignment 2
Slide 9
Physical Implementation - 1
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44220: Database Design & Implementation: Review & Assignment 2
Slide 10
Physical Implementation - 2
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The ‘Team’ Table has composite Primary Key, consisting of BOTH;
 CourseCode & StaffID
You MUST set up relationships between ALL of the Tables of your
Database, with referential integrity enforced, BEFORE you;
 ADD any DATA to your Tables,
 BUILD any QUERIES to answer Questions.
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44220: Database Design & Implementation: Review & Assignment 2
Slide 11
Implementing ‘rules’ of Domains
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Access provides 4 main ways to control the data
that can be entered into individual fields.
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Data Type
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Field Size (or Format)
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to control the range of allowable values that can be
entered into a field.
Input Mask
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depends upon the Data Type chosen.
Validation Rule
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Number, Text, Memo, Date/Time, Currency, etc.
to force the data that is entered to conform to a
particular shape/pattern.
44220: Database Design & Implementation: Review & Assignment 2
Slide 12
Assignment 2 (50% of Module Marks)
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Deadline?
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Read the Case Study carefully:
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Friday, the 9th of May.
Your Database MUST be able to ‘answer’ the 10
questions at the end of the Learn-by-Post Case
Study.
Two parts:
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implement your logical data model as a physical data
model, using Microsoft Access;
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Using Data Type, Field Size, Input Masks & Validation
Rules as appropriate in order to constrain domains.
test this implementation thoroughly, by building 10
Database Queries;
 i.e. prove that the information requirements can
actually be delivered.
44220: Database Design & Implementation: Review & Assignment 2
Slide 13
Answer the Questions I have set!
1. Implement a Physical Data Model, i.e. a Microsoft
Access Database; which supports requirements of
the Case Study organisation. (50 Marks)
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This Physical Data Model MUST be developed using
Microsoft Access.
Marks here will be awarded with respect to the
following:
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Tables – are there sensible Table Names, Field Names &
choice of Key Fields.
Domains – how well have you attempted to control data
entry by use of Data Type, Field Size, Input Mask,
Validation Rule, etc.
Relationship Diagram – does it show all of the
relationships, with referential integrity enforced,
between the all of the above Tables?
 NB. If you can’t enforce referential integrity for
every relationship, then there is a problem with your
database design/implementation.
44220: Database Design & Implementation: Review & Assignment 2
Slide 14
Answer the Questions I have set!
2. Test this Physical Data Model; by developing a
number of Queries that show that your database can
deliver the information requirements, i.e. can answer
the 10 questions from the Case Study. (50 Marks)
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These Database Queries MUST be developed using
Microsoft Access.
You MUST develop 10, clearly named, queries (each worth
5 Marks) that provide ‘reasonable’ answers to the
Questions of the Case Study organisation; e.g.:
A. Who are our students?
B. Which tutors are module co-ordinators, and for which
modules?
C. Which students should be sent a certificate for module X?
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AND remember to ADD ‘enough’ test data to your database
tables;
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in order to demonstrate that your Database can provide a
‘reasonable’ answer to each of the 10 questions.
44220: Database Design & Implementation: Review & Assignment 2
Slide 15
The 10 Questions (5 Marks each)
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Your database MUST be able to ‘answer’ the following questions:
A. Who are our students?
B. Which students should attend examination centre X?
C. What is the assessment/examination weighting for all of the
available modules?
D. Which tutor(s) is/are on the team for module X?
E. Which tutors are module co-ordinators, and for which modules?
F. Which module(s) has student X already taken?
G. What module(s) is/are student X currently studying?
H. Which modules are not yet fully marked & who is the module coordinator?
I. Which students should be sent a certificate for module X?
J. Which module is the most difficult to pass?
NB. Where the examination centre, module, or student is an X, then
the user of the Database MUST be able to choose from at least 2
different values. Therefore, the queries that ‘answer’ these questions
MUST BE parameter-based queries.
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44220: Database Design & Implementation: Review & Assignment 2
Slide 16
Get on with it!
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No More Lectures
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TWO Assignment 2 Support Workshops
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i.e. this week & next.
If you want any help with Assignment 2, then
make sure that you come to these support
sessions prepared to ask sensible questions.
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You may be ‘glad’ to hear?
“Where do I begin?” - is NOT a sensible
question!
Assignment 2 Deadline:
th of May.
 Friday, the 9
Ian Perry
44220: Database Design & Implementation: Review & Assignment 2
Slide 17