Database Systems
Information Systems
Intermediate 2
Data and Information



Data is raw, unprocessed facts and figures.
Data is collected, stored and processed by
computers.
Examples:





368
HR101FE
010468
Baker
25168
Data and Information



Information is processed data with structure
or meaning.
Information is useful to humans.
Examples:





Age: 36 years 8 months
Post Code: HR10 1FE
Date of Birth: 01/04/68
Occupation: Baker
Total Spent: £251.68
What is a database?



A database is a collection of related
information about a set of persons or objects.
Traditionally, databases have been manual
paper based systems.
Example: the “Yellow Pages”
What is a database
management system?


A database management system (DBMS)
is a software package which is used to create,
manipulate and present data from electronic
databases.
Example of DBMSs include Microsoft Access
and Filemaker Pro.
Traditional databases






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storage of paper records was very bulky
easy to mis-file a record, or records to be lost or
damaged
data often duplicated in several records
keeping records up-to-date was difficult and time
consuming, and often resulted in data inconsistency,
where duplicated values were updated in one record
but not in others
many people employed to maintain the records,
which was costly
searching for records was time consuming
producing reports, such as sorted lists or data
collated from several sources, was extremely time
consuming, if not impossible
Case Study: DVD Rentals
Member Number
1012
1034
1056
1097
Title
Miss
Mr
Mr
Mrs
Forename
Isobel
John
Fred
Annette
Surname
Ringer
Silver
Flintstone
Kirton
Telephone No.
293847
142536
817263
384756
Case Study: DVD Rentals
DVD Code
002
003
Title
Finding Nemo
American Pie
Cost
£2.50
£2.50
008
011
The Pianist
Notting Hill
£2.50
£2.50
014
015
Prime Suspect £2.00
Shrek
£1.50
Date Out
03/09/04
27/08/04
01/09/04
04/09/04
27/08/04
04/09/04
27/08/04
10/09/04
Date Due
04/09/04
28/08/04
02/09/04
06/09/04
28/08/04
06/09/04
28/08/04
11/09/04
Member Number Name
1034
John Silver
1056
F Flintstone
Isobel Ringer
1097
Annette Kirton
1012
I Ringer
1086
F Flintstone
Annette Kirton
1034
Joan Silver
Benefits of computerised
databases



Searching, sorting and calculating
operations can be performed much
more quickly and easily.
Information is more easily available to
users, due to improved methods of data
retrieval.
Data integrity is improved resulting in
more accurate information.
Types of computerised
database


Flat file
Relational
Flat file databases
DVD
Code
Title
Cost
Date Out
Date Due
Member
Number
002
Finding Nemo
£2.50
03/09/04
04/09/04
1034
John Silver
142536
003
American Pie
£2.50
27/08/04
28/08/04
1056
Fred Flintstone
817263
003
American Pie
£2.50
01/09/04
02/09/04
1012
Isobel Ringer
293847
008
The Pianist
£2.50
04/09/04
06/09/04
1097
Annette Kirton
384756
011
Notting Hill
£2.50
27/08/04
28/08/04
1012
Isobel Ringer
293847
011
Notting Hill
£2.50
04/09/04
06/09/04
1056
Fred Flintstone
817263
014
Prime Suspect £2.00
27/08/04
28/08/04
1097
Annette Kirton
384756
015
Shrek
10/09/04
11/09/04
1034
Joan Silver
142536
£1.50
Name
Telephone
Number
Limitations of flat file
databases


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Data is very likely to be duplicated.
The duplication of data leads to the possibility
of data inconsistency.
It is not possible to store information about a
member without entering details of a DVD.
This is called an insertion anomaly.
Removing a DVD from the database may
remove the only record which stores details
of a Member. This is called a deletion
anomaly.
Relational databases


A relational database stores data in
more than one table.
The idea is to ensure that data is only
entered and stored once, so removing
the possibility of data duplication and
inconsistency.
Entities and Data
Relationships

An entity represents a person or object.


e.g. Member, DVD Rental
Each entity has a set of attributes which
describe examples or instances of that
entity.


The attributes of the DVD Rental entity are code,
title, cost, date out, date due and member number
The attributes of the Member entity are member
number, name and telephone number.
Entities, Attributes and
Instances
MEMBER
Member
Number
1012
Member Name
Isobel Ringer
Telephone
Number
293847
1034
John Silver
142536
1056
Fred Flintstone
817263
1097
Annette Kirton
384756
Entities, Attributes and
Instances
The Member entity
is the whole table
MEMBER
Member
Number
1012
Member Name
Isobel Ringer
Telephone
Number
293847
1034
John Silver
142536
1056
Fred Flintstone
817263
1097
Annette Kirton
384756
Entities, Attributes and
Instances
The Member entity
Each
column
is the whole table
attribute, e.g. Member Name
MEMBER
Member
Number
1012
Member Name
Isobel Ringer
Telephone
Number
293847
1034
John Silver
142536
1056
Fred Flintstone
817263
1097
Annette Kirton
384756
stores
one
Entities, Attributes and
Instances
The Member entity
Each
column
stores
one
is the whole table
attribute, e.g. Member Name
MEMBER
Member
Number
1012
Member Name
Isobel Ringer
Telephone
Number
293847
1034
John Silver
142536
1056
Fred Flintstone
817263
1097
Annette Kirton
384756
Each row stores one instance,
e.g. Member 1034
Entities, Attributes and
Instances

An entity represents a person or object.


e.g. Member, DVD Rental
Each entity has a set of attributes which
describe examples or instances of that
entity.


The attributes of the DVD Rental entity are code,
title, cost, date out, date due and member number
The attributes of the Member entity are member
number, name and telephone number.
Data Relationships

Three types of relationship:
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
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One-to-one
One-to-many
Many-to-many
Data Relationships

One-to-one
VEHICLE
REGISTRATION
NUMBER
Data Relationships

One-to-one
MEMBER

One-to-many
DVD RENTAL
VEHICLE
REGISTRATION
NUMBER
Data Relationships

One-to-one
MEMBER

REGISTRATION
NUMBER
One-to-many
DVD RENTAL

VEHICLE
Many-to-many
PUPIL
TEACHER
More than one table
Member Member
Number Name
Telephone
Number
04/09/04
1012
Isobel Ringer
293847
American Pie 3 £2.50 01/09/04
02/09/04
1034
John Silver
142536
008
The Pianist
£2.50 04/09/04
06/09/04
1056
Fred Flintstone 817263
011
Notting Hill
£2.50 04/09/04
06/09/04
1097
Annette Kirton 384756
014
Prime Suspect
£2.00 27/08/04
28/08/04
015
Shrek
£1.50 10/09/04
11/09/04
003
American Pie 3 £2.50 27/08/04
28/08/04
011
Notting Hill
28/08/04
DVD
Code Title
Cost
002
Finding Nemo
£2.50 03/09/04
003
Date Out Date Due
£2.50 27/08/94

but there’s a
problem…
More than one table
Member Number Member Name
Telephone Number DVD Code
1012
Isobel Ringer
293847
003
1034
John Silver
142536
?
1056
Fred Flintstone
817263
011
1097
Annette Kirton
384756
?
DVD Code Title
Cost
Date Out Date Due
002
Finding Nemo
£2.50
03/09/04
04/09/04
003
American Pie 3
£2.50
01/09/04
02/09/04
008
The Pianist
£2.50
04/09/04
06/09/04
011
Notting Hill
£2.50
04/09/04
06/09/04
014
Prime Suspect
£2.00
27/08/04
28/08/04
015
Shrek
£1.50
10/09/04
11/09/04
003
American Pie 3
£2.50
27/08/04
28/08/04
011
Notting Hill
£2.50
27/08/94
28/08/04
More than one table
Member Number Member Name
Telephone Number
1012
Isobel Ringer
293847
1034
John Silver
142536
1056
Fred Flintstone
817263
1097
Annette Kirton
384756
DVD Code
Title
Cost
Date Out
Date Due
Member Number
002
Finding Nemo
£2.50
03/09/04
04/09/04
1034
003
American Pie 3
£2.50
01/09/04
02/09/04
1012
008
The Pianist
£2.50
04/09/04
06/09/04
1097
011
Notting Hill
£2.50
04/09/04
06/09/04
1056
014
Prime Suspect
£2.00
27/08/04
28/08/04
1097
015
Shrek
£1.50
10/09/04
11/09/04
1034
Keys
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A key is a field, or set of fields, whose
values uniquely identify a record.
In any table, there may be more than
one field, or set of fields, which can
uniquely identify each record—these are
called candidate keys.
The candidate key which is chosen to
be used is called the primary key.
Keys


Member Number Member Name
Telephone Number
1012
Isobel Ringer
293847
1034
John Silver
142536
1056
Fred Flintstone
817263
1097
Annette Kirton
384756
Member Number is a candidate key for
the Member entity
MEMBER(Member Number, Name, Telephone Number)
Keys
DVD Code
Title
Cost
Date Out
Date Due
Member Number
002
Finding Nemo
£2.50
03/09/04
04/09/04
1034
003
American Pie 3
£2.50
01/09/04
02/09/04
1012
008
The Pianist
£2.50
04/09/04
06/09/04
1097
011
Notting Hill
£2.50
04/09/04
06/09/04
1056
014
Prime Suspect
£2.00
27/08/04
28/08/04
1097
015
Shrek
£1.50
10/09/04
11/09/04
1034
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DVD Code is a candidate key for the DVD Rental
entity
DVD RENTAL(DVD Code, Title, Cost, Date Out, Date
Due, *Member Number)
Member Number is called a foreign key.
Keys
DVD Code
Title
Cost
Date Out
Date Due
Member Number
002
Finding Nemo
£2.50
03/09/04
04/09/04
1034
003
American Pie 3
£2.50
01/09/04
02/09/04
1012
008
The Pianist
£2.50
04/09/04
06/09/04
1097
011
Notting Hill
£2.50
04/09/04
06/09/04
1056
014
Prime Suspect
£2.00
27/08/04
28/08/04
1097
015
Shrek
£1.50
10/09/04
11/09/04
1034



DVD Code is a candidate key for the DVD Rental
entity
DVD RENTAL(DVD Code, Title, Cost, Date Out, Date
Due, *Member Number)
Member Number is called a foreign key.
Keys
A foreign key is a field which is not a primary
key in its own table, but is a primary key in
another table.
 Member Number is a foreign key in the DVD
table, because it is the primary key in the
Member table.
 Here is the data model:
MEMBER(Member Number, Name, Telephone
Number)
DVD RENTAL(DVD Code, Title, Cost, Date Out,
Date Due, *Member Number)

Implementation

3 steps:
Set-up the tables
 Populate the tables
 Manipulate and present the data

Setting up the tables
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

Which tables are required?
Which fields are required?
What are the properties of each field?
Setting up the tables

Which tables are required?
The tables correspond directly to the
entities in the data model.
 In this case, there will be two tables,
Member and DVD Rental.

Setting up the tables

Which fields are required?

The fields in each table are the
attributes in each entity in the data
model.
Setting up the tables

What are the properties of each field?
 Its name

be consistent!
Setting up the tables

What are the properties of each field?
 Its name
 Its data type
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text
numeric (integer, real, currency)
date or time
Boolean (yes or no)
link
object
Setting up the tables

What are the properties of each field?
 Its name
 Its data type
 Validation:
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Presence check
Restricted Choice check
Range check
Populating the tables
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Take care to be accurate
Validation: make sure the data is
sensible
Verification: make sure the date is
correct
Verification methods:

Bar codes, OCR
Manipulating the Data
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
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
Searching records
Sorting records
Calculating values
Presenting results
Searching

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Which fields will be used to identify
the records required?
What are the search conditions for
identifying the records required?
Which fields will be displayed?
E.g. Search for Test 3 = 10
“Test 3 = 10” is called the search
condition
Searching: Boolean operators
Operator
Meaning
Example
=
equal to
Age = 16
Surname = “Smith”
<>
not equal to
Height < > 1.70
Certificate < > “PG”
>
greater than
or
after
Age > 17
Surname > “N”
Date of Birth > 01/05/1952
<
less than
or
before
Height < 1.9
Surname < “N”
Date of Birth < 31/06/1990
>=
greater than or equal to
or
after and including
Age >= 17
Postcode >= “EH30”
Date of Birth >= 01/05/1952
<=
less than or equal to
or
before and including
Height <= 1.95
Postcode <= “EH20”
Date of Birth <= 30/06/1990
Searching: wildcard characters
Searching: wildcard characters
Character
*
Description
Example
wh* matches what,
Matches any number of characters (zero or more). It can
when, where, who, why,
be used as the first or last character in the character string.
white, etc.
Matches any single alphabetic character.
b?ll matches ball, bell,
bill and bull
Matches any single character within the brackets.
b[ae]ll matches ball and
bell but not bill or bull
Matches any character not in the brackets.
b[!ae]ll matches bill and
bull but not ball or bell
–
Matches any one of a range of characters. You must
specify the range in ascending order (A to Z, not Z to A).
b[a-c]d matches bad,
bbd, and bcd
#
Matches any single numeric character.
1#3 matches 103, 113,
123, etc.
?
[]
!
Wildcard Searches

Search for Surname = “*son”
Complex Searches





A complex search involves more
than one search condition (and usually
more than one field)
Search
Search
Search
Search
for
for
for
for
Test
Test
Test
Test
3
3
3
3
=
=
>
<
10 AND Average > 6
10 OR Average > 6
5 AND Test 3 < 8
2 OR Test 3 >9
Sorting


Which field will be used to decide the
order of records? This is called the
sort key.
For the sort key, will the order of
sorting be ascending or descending?
Sorting
For a list of people with the tallest first


For a list of people with youngest first


sort in ascending order of age
For alphabetical order



sort in descending order of height
sort in ascending order of surname
“ascending order of surname” is called
the sort condition
Complex Sorting



A complex sort involves more than one
sort condition involving two or more fields.
The main sort key is called the primary
sort key, and the second one is called the
secondary sort key.
“Telephone book” order:

Ascending order of Surname, then
Ascending order of Forename
Calculating

Use formulas or expressions to calculate
a value for a record based on other
values in the record
Presenting




Use Layouts (Filemaker Pro)
Use forms and reports (Microsoft
Access)
Which fields are required?
Perform a search and/or sorting
operation and present the results