1. Created by M Nodalo, Port Moresby International School for Year 11 Information
Technology (T) - ACT/BSSS, revised 2010

2. Objective
So that students will be able –
 to discuss the basic database concepts and terminologies
– data, information, field, record, key field, computed
fields, field length, data types, etc.
 To discuss the concept of relational database and flat-file
database
 To discuss the concept of SQL (structured query language)

3. Data Vs. Information
 Data – raw fact or figures
Example : Max Freeman 55,000 25
 Information – data that have been
processed to be meaningful to the user
Example: K55,000 x .25 = K13,750
Max Freeman is a salesman who earned K55,000 sales for
this month and therefore, receives 25% commission which
is K13,750.

4. Stages of Processing Data
Input processing Output
data information• Calculating
• Sorting
• Classifying
• Analysing
• Summarising
• reporting

5. What is a Database?
 An organised collection of data items that are related to
a particular topic, purpose or activity
Examples:
 a telephone directory, an address book, student class
list

6. Databases can be stored
 Manually (in a filing
cabinet with index
cards, 3-ring binders,
file folders)
 Electronically using a
computer system
(with suitable
database software)

7. Manual databases - concerns
 Data duplication – same data on each file
 Effects of data duplication:
 More space is taken up by the files
 More work is needed to retrieve the
information

8. Advantages of Computerised
Databases over Paper files
 Easier to store large volume of information
 Easier to retrieve information quickly /flexibly
 Speed of information processing
 Versatility/flexibility in organising & reorganising
information
 Easier to display, print & distribute information in a
variety of ways
 Validation checks may be made on the data (done by
a computer program)

9. Disadvantages of Computerised
database over paper files
 Unable to access data when there’s a computer
breakdown
 Ease of copying computer files; passwords
needed for extra protection
 Extra cost & time to train people to use the
database

10. Planning a Database
 Define the purpose of the database
 Determine the type of output reports
 List all the data items (determines the fields)

11. Database Structure
 Table – a collection of related records
 Record – a collection of data about a person or thing
made up of one or more fields
 Field – a single piece of data or information common
to all records
file
record
Name: Venus Jackson
Age: 27
Home Address: Gere-gere Ave.,
Boroko, NCD
Gender: Female
Job Position: Accounts Clerk
Pay Rate/FN: 750.00
Years in Service: 5
fields
Employee file

12. Example of a Database
Telephone Directory
Telephone Directory
Name Address Phone Number
Aldo,Mark East Boroko 323-2932
Amani,James Hohola 325-9022
Artona,Kathy Port Moresby 323-4325
records
File/table name
Field data
Field name

13. Two parts of a field:
1. Field name – words that represent each field data
or information, e.g.
name, address, phone number, etc.
2. Field data – the actual data or
information item stored in a field,
e.g. Mary Jones, Boroko, 325-3423

14. Designing a Record
 Field names
 Type of data (text, numeric, date, boolean,
image)
 Field length or size – the total number of
characters allowed for a particular field
 Field description

15. Field length/size
 Should be designed to cope with the largest
entry possible without reserving unnecessary
disk space
 Too long field sizes –
- will take up more space on the storage
media (floppy/hard disk/CDs/flash drives)
- takes longer to process

16. Types of Data
Numeric – contains only numbers
Character text – numbers, letters &
other symbols can be entered
Date – date is entered as 01/09/04
Logical (Boolean) – allows Y/N (yes/no)
or T/F (true/false)
Image/Picture

17. Key Field
 A field that may be used to search a file
 It makes a record unique from other records in
the file
e.g. student ID number, Book ID number,
employee ID, customer code

18. Computed field
 Contain formulas similar to spreadsheet
formula
 They display values calculated from values in
other numeric fields
 Example: Net Pay may contain formula which
calculates an employee’s net pay using Gross
Pay and Tax fields

19. Field Name Data type Field size/length Description
Sample database: Student file

20. Features of Computerised
Databases
 Create fields
 Add and alter records
 Search for specific records
 Sort records
 Print reports

21. What is DBMS?
 DBMS – Database Management System
 A computer program that allows you to set up a
database on computer.
 build a database
 add new data, delete or edit existing data
 search and extract specific data based on certain criteria
(query)
 change/alter the structure of the data file
 sort and reorganise data
 display data on screen / print reports
 security of allowing certain people to access files

22. What is MS Access?
 An example of a DBMS which was
developed by Microsoft Corporation.

23. Database Terms in Access
Fields (columns)
Records
(rows)
table – refers to a file in Access

24. Database Queries
 Issues
 the incompatibility of database languages
 created difficulty for people using different
applications to access the same database
 E.F. Codd (IBM) – proposed the standardized
structured English Query Language or what
evolved as the SQL

25. Structured Query Language (SQL)
 Not a database management system
 Not a full-featured programming language like Java or
C+.
 It is a sublanguage tailored for the database
environment
 SQL statements – embedded inside computer
programs such as COBOL, C or other programming
languages
 SQL statements – understood by MS Acccess, MS SQL
Server, DB2, Oracle, Sybase & other database
programs

26. Structured Query Language (SQL)
 Combines database concepts of
 Tables/files
 Records (rows)
 Fields (columns)
 Mathematical concept of set
 See example on pages 234-235 (Chapter 7 Database
Applications and Privacy Implications, Tomorrow’s
Technology and You) – 7.1 The Language of Database
Queries

27. Structured Query Language (SQL)
 Basic SQL statements – filters the records of a
database to be able to extract only those
records that meet specific criteria
 SQL statement format:
 SELECT (specify fields to extract)
 FROM (specify source – file name)
 WHERE (specify criteria or condition using appropriate comparison
operators such as AND, OR, NOT, =, >, <, <>, >=, <=)

28. Types of Databases
• Flat file database – uses only one file at a
time
Example: MS Excel – spreadsheet list
• Relational database – consists of several
files in which data can be accessed
simultaneously
Example: MS Access

29. Relational Database
Relational database links some tables with
certain data common with other tables.

30. Sources
• Chapter 7 – Database Applications & Privacy
Implications, Tomorrow’s Technology and You (8th ed)
by G. Beekman & M. Quinn