Download Flat File Database

Information Systems Design and Development
Databases
A database is a collection of data or information which is held
together in an organised or logical way.
Today databases exist almost entirely on
computer systems. A database is made
up of a file, records and fields.
Link 1 – What is an information System?
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File
Data is stored in files. A file is a collection of data on one topic
in a simple database. Files are made up of sets of records.
Record
A record is all the information about one person or thing in the
file, for example one book in a book database. Records can be
updated, deleted or new records can be inserted.
Field
Each bit of information in a record is stored in a field. Each field
has a field name eg title in a book database. Fields can be
deleted or added.
Link 2 – What is a Database?
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Field Types
Number – stores numbers, e.g. exam marks
Text – stores words or numbers not being used for calculations, e.g.
surname, phone no.
Graphic - stores images, e.g. photographs
Date - stores dates, e.g. date of birth
Time – stores a time of day, e.g. the start time of an exam
Calculated – stores a formula and uses 1 or more of the other fields to
carry out a calculation. The answer is displayed. e.g. averages or totals
Object (OLE) field. In Microsoft Access, for example, an object field can
hold a word document, an Excel spreadsheet or a Paint graphic.
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More Field Types
Boolean – stores just two values, eg. ‘Yes’ or ‘’No’. Eg. Married?
Link - stores a hyperlink within the database or a hyperlink to a
document outside the database. e.g. To another record or to an
Internet site.
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Validation
Validation is the process of checking that data
entered into a system makes sense and is allowable.
Types of validation check:




Presence check
Restricted choice
Field length check
Field range check
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Presence Check
Checks that data has been entered and
that the data field has not been left blank.
Restricted Choice Forces the user to enter data from a list of
acceptable values e.g. from a dropdown
menu with the days of the week.
Field Length Check
Checks that the data entered is of a
certain length e.g. year with 4 digits.
Field Range Check
Checks that the data entered is within a
certain range of numbers e.g. month
entered should be from 1 to 12.
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Searching
Using one or more fields to search for records from the
database.
Sorting
Putting the records into some kind of order.
Records can be sorted into ascending or descending order.
More than one sort can be carried out. e.g.
First Name
Abby
Carol
Alison
John
Robert
Sally
Surname
Brown
Brown
Campbell
Green
McDonald
McDonald
A primary sort has been
done on the ‘Surname’
field then a second sort on
the ‘First Name’ field.
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Flat File Database
A simple database structure has one table containing all the
fields and the data they contain.
Relational Database
A database which contains more than one table. The tables
are linked together via a relationship between the primary key
of one table and the foreign key of another table. Relational
databases reduce data duplication and data inconsistency.
Key Field – a field in a record that is used to uniquely identify a
record in the database eg. reference number, account number.
Link 3 – More About Databases
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A primary key field and a foreign
key field are used to make
relationships between tables.
A primary key uniquely identifies each record in a database.
For example, a primary key could be an ID number or an
account number. A Table can only have 1 primary key.
A foreign key enables you to set up relationships, or links,
between tables in a database.
Link 4 – Even More about Databases
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Look at the following flat file database. The data stored
shows flights leaving Glasgow airport and the pilot who will
captain the flight.
Look for data duplication and data inconsistency
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Example 1 Flights Database
Flight ID Date
Destination Pilot ID
Surname
Forename Salary
(£)
EZ2580
12/03/14
London
PID0001
Casey
Nicola
50,000
EZ3210
14/13/14
Paris
PID0002
Smith
James
46,500
EZ2550
14/03/14
Dublin
PID0001
Casey
Nicolas
50,000
BA1231
12/03/14
Rome
PID1001
Miller
JohnData inconsistency
50,000
BA1229
14/03/14
Madrid
PID1001
Miller
John
50,000
AA0981
14/03/14
New York
PID2001
Murray
Anne
65,000
AA0985
17/03/14
LA
PID2001
Murray
Anne
65,000
Data duplication
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Example 1 Flights Database
In order to split a table into two tables you need to decide:
1. How the data in the table will be split.
• It could be library members and the books they borrow.
• It could be teachers and the pupils they teach.
2. What are the primary and foreign keys?
• Decide on the primary key for each table.
(the primary key must be unique for each record).
• Decide which field will link the tables. This will be the primary key
in one table and becomes the foreign key in the other table.
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Flight Table
Pilot Table
Duplications can be removed
Link
Flight ID
Date
Destination
Pilot ID
Surname
Forename
Salary
(£)
EZ2580
12/03/14
London
PID0001
Casey
Nicola
50,000
EZ3210
14/13/14
Paris
PID0002
Smith
James
46,500
EZ2550
14/03/14
Dublin
PID0001
Casey
Nicolas
50,000
BA1231
12/03/14
Rome
PID1001
Miller
John
50,000
BA1229
14/03/14
Madrid
PID1001
Miller
John
50,000
AA0981
14/03/14
New York
PID2001
Murray
Anne
65,000
AA0985
17/03/14
LA
PID2001
Murray
Anne
65,000
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Example 1 Flights Database
We can now split this flat file into two tables, one table to store
the flight details and the other to store the pilot details.
Foreign Key Primary Key
Primary Key
Flight
ID
Date
Destina
tion
Pilot ID
Pilot ID
Surname
Forename
Salary
(£)
EZ2580
12/03/14
London
PID0001
PID0001
Casey
Nicola
50,000
PID0002
Smith
James
46,500
PID1001
Miller
John
50,000
PID2001
Murray
Anne
65,000
EZ3210
14/13/14
Paris
PID0002
EZ2550
14/03/14
Dublin
PID0001
BA1231
12/03/14
Rome
PID1001
BA1229
14/03/14
Madrid
PID1001
AA0981
14/03/14
New
York
PID2001
AA0985
17/03/14
LA
PID2001
Flight Table
Pilot Table
We then link the two tables
on the PilotID field .
PilotID is known as the
foreign key in the Flight table.
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Example 2 Library Database
Member ID
Member
Name
KP102
Mary Smith
Data duplication
KP982
James
Main
Telephone
Book
Reference
Book title
Date
Borrowed
987 2650
BK345
The Green
Mile
17/01/14
967 3641
BK287
The Dark
Tower
15/01/14
KP102
Mary Smith
987 2650
BK290
Pride and
Prejudice
17/01/14
KP982
Jimmy
Main
967 3641
BK205
Emma
15/01/14
KP982
James
Main
967 3641
BK106
A Fine
Balance
20/01/14
945 2351
BK239
Sunset
Song
21/01/14
KP345
Jo Jones
Data inconsistency
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Link
Book Table
Member Table
Member ID
Member
Name
Telephone
Book
Reference
Book title
Date
Borrowed
KP102
Mary Smith
987 2650
BK345
The Green
Mile
17/01/14
KP982
James Main 967 3641
BK287
The Dark
Tower
15/01/14
KP102
Mary Smith
987 2650
BK290
Pride and
Prejudice
17/01/14
KP982
Jimmy Main 967 3641
BK205
Emma
15/01/14
KP982
James Main 967 3641
BK106
A Fine
Balance
20/01/14
KP345
Jo Jones
BK239
Sunset
Song
21/01/14
945 2351
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Example 2 Library Database
We can now split this flat file into two tables.
Foreign Key Primary Key
Member Table
Book Table
Primary Key
Member Telephone
Name
Member
ID
Mary
Smith
987 2650
KP102
James
Main
967 3641
KP345
Jo Jones
945 2351
KP982
We then link the two tables
on the MemberID field.
MemberID is known as the
foreign key in the Book table.
Member
ID
Book
Reference
Book
title
Date
Borrowed
KP102
BK345
The
Green
Mile
17/01/14
KP982
BK287
The Dark
Tower
15/01/14
KP102
BK290
Pride and 17/01/14
Prejudice
KP982
BK205
Emma
15/01/14
KP982
BK106
A Fine
Balance
20/01/14
KP345
BK239
Sunset
Song
21/01/14
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Example 3 Police Database
Surname Forename
Nickname Sex
Heigh
t (M)
CrimeType
Date
Arrested
Police Ref
ID
Mathers
Michael
Eminem
Male
1.68
Burglary
12/03/13
GCR001
Smith
Kevin
Smithy
Male
1.54
Kidnap
03/06/12
GCR320
Mitchell
Gary
Gazza
Male
1.80
Forgery
08/11/12
GCR458
Smith
Kevin
Smithy
Male
1.54
Assault
13/07/13
GCR239
Mathers
Michael
Eminem
Male
1.68
Bank Robbery
13/06/13
GCR289
Mitchell
Gary
Gazza
Male
1.54
Hacking
09/06/13
GCR310
Jones
Anne
JoJo
Female 1.32
Dangerous
driving
13/06/13
GCR201
Link?
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Example 3 Police Database
• In this example we want to split the database into
two tables, one containing the data about a criminal
and the other containing the data about the crime.
• However in the criminal table there is no obvious
primary key. When this happens another field should be
added that will become the primary key. This can simply
be an autonumber field.
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Criminal Table
Crime Table
ID
Surname
Forename
Nickname
Sex
Height (M)
Crime
Type
Date
Arrested
Police
Ref
ID
1
Mathers
Michael
Eminem
Male
1.68
Burglary
12/03/13
GCR001
2
Smith
Kevin
Smithy
Male
1.54
Kidnap
03/06/12
GCR320
3
Mitchell
Gary
Gazza
Male
1.80
Forgery
08/11/12
GCR458
2
Smith
Kevin
Smithy
Male
1.54
Assault
13/07/13
GCR239
1
Mathers
Michael
Eminem
Male
1.68
Bank
Robbery
13/06/13
GCR289
3
Mitchell
Gary
Gazza
Male
1.54
Hacking
09/06/13
GCR310
4
Jones
Anne
JoJo
Female
1.32
Dangerous
driving
13/06/13
GCR201
Link
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Example 3 Police Database
We have split this flat file into two tables.
Primary Key
Criminal Table
Criminal Surname Forename Nickname
ID
Sex
Height (M)
1
Mathers
Michael
Eminem
Male
1.68
2
Smith
Kevin
Smithy
Male
1.54
3
Mitchell
Gary
Gazza
Male
1.80
4
Jones
Anne
JoJo
Female
1.32
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Example 3 Police Database.
Primary Key
Crime Table
Foreign Key
Crime Type
Date Arrested
Police Ref ID
Criminal ID
Burglary
12/03/13
GCR001
1
Kidnap
03/06/12
GCR320
2
Forgery
08/11/12
GCR458
3
Assault
13/07/13
GCR239
2
Bank Robbery
13/06/13
GCR289
1
Hacking
09/06/13
GCR310
3
Dangerous driving 13/06/13
GCR201
4
The two tables are linked by the Criminal ID field.
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Example 4 Music Instructors
The next example is a database containing a list of music
instructors and the students they teach.
The table contains data duplication and needs to broken into
2 tables that are linked by one field.
Consider
• what the two tables should be
• what the primary key for each table should be
• what the foreign key should be
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Example 4 Music Instructors
Instructor
Instrument
Cost
per
lesson
Student
Forename
Student
surname
Age
Email
Mrs Keys
Piano
£20.00
John
Smith
17
[email protected]
Mrs Keys
Piano
£20.00
David
Beckham
21
[email protected]
Mr Bell
Clarinet
£18.00
Mary
Hamilton
15
[email protected]
Mr Bell
Clarinet
£18.00
Kevin
Bridges
20
[email protected]
Ms Watt
Violin
£18.00
Miley
Cyrus
15
[email protected]
Ms Watt
Violin
£18.00
Alex
Salmond
20
[email protected]
Ms Watt
Violin
£18.00
Ada
Lovelace
19
[email protected]
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Example 4 Music Instructors
Instructor Table
Primary Key
Instructor
ID
1
Teacher
Instrument
Mrs Keys
Piano
Cost per
lesson
£20.00
2
Mr Bell
Clarinet
£18.00
3
Ms Watt
Violin
£18.00
Autonumber field added
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Example 4 Music Instructors
Primary Key
Student Table
Foreign Key
Student
Forename
Student
Surname
Age
Email
Instructor
ID
John
Smith
17
[email protected]
1
David
Beckham
21
[email protected]
1
Mary
Hamilton
15
[email protected]
2
Kevin
Bridges
20
[email protected]
2
Miley
Cyrus
15
[email protected]
3
Alex
Salmond
20
[email protected]
3
Ada
Lovelace
19
We then link the two tables on the
[email protected]
3
Instructor ID field.
The two tables are linked by the Instructor ID field.
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Music Instructors in Access
Let’s now look at the implementation of this data in MS
Access.
Link to Access file
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