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Created by M Nodalo, Port Moresby International School for Year 11 Information
Technology (T) - ACT/BSSS, revised 2010
Objective
So that students will be able –
 to discuss the basic database concepts and terminologies
– data, information, ...
Data Vs. Information
 Data – raw fact or figures
Example : Max Freeman 55,000 25
 Information – data that have been
proc...
Stages of Processing Data
Input processing Output
data information• Calculating
• Sorting
• Classifying
• Analysing
• Summ...
What is a Database?
 An organised collection of data items that are related to
a particular topic, purpose or activity
Ex...
Databases can be stored
 Manually (in a filing
cabinet with index
cards, 3-ring binders,
file folders)
 Electronically u...
Manual databases - concerns
 Data duplication – same data on each file
 Effects of data duplication:
 More space is tak...
Advantages of Computerised
Databases over Paper files
 Easier to store large volume of information
 Easier to retrieve i...
Disadvantages of Computerised
database over paper files
 Unable to access data when there’s a computer
breakdown
 Ease o...
Planning a Database
 Define the purpose of the database
 Determine the type of output reports
 List all the data items ...
Database Structure
 Table – a collection of related records
 Record – a collection of data about a person or thing
made ...
Example of a Database
Telephone Directory
Telephone Directory
Name Address Phone Number
Aldo,Mark East Boroko 323-2932
Ama...
Two parts of a field:
1. Field name – words that represent each field data
or information, e.g.
name, address, phone numbe...
Designing a Record
 Field names
 Type of data (text, numeric, date, boolean,
image)
 Field length or size – the total n...
Field length/size
 Should be designed to cope with the largest
entry possible without reserving unnecessary
disk space
 ...
Types of Data
Numeric – contains only numbers
Character text – numbers, letters &
other symbols can be entered
Date – d...
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. stude...
Computed field
 Contain formulas similar to spreadsheet
formula
 They display values calculated from values in
other num...
Field Name Data type Field size/length Description
Sample database: Student file
Features of Computerised
Databases
 Create fields
 Add and alter records
 Search for specific records
 Sort records
 ...
What is DBMS?
 DBMS – Database Management System
 A computer program that allows you to set up a
database on computer.
...
What is MS Access?
 An example of a DBMS which was
developed by Microsoft Corporation.
Database Terms in Access
Fields (columns)
Records
(rows)
table – refers to a file in Access
Database Queries
 Issues
 the incompatibility of database languages
 created difficulty for people using different
appl...
Structured Query Language (SQL)
 Not a database management system
 Not a full-featured programming language like Java or...
Structured Query Language (SQL)
 Combines database concepts of
 Tables/files
 Records (rows)
 Fields (columns)
 Mathe...
Structured Query Language (SQL)
 Basic SQL statements – filters the records of a
database to be able to extract only thos...
Types of Databases
• Flat file database – uses only one file at a
time
Example: MS Excel – spreadsheet list
• Relational d...
Relational Database
Relational database links some tables with
certain data common with other tables.
Sources
• Chapter 7 – Database Applications & Privacy
Implications, Tomorrow’s Technology and You (8th ed)
by G. Beekman &...
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Database concepts presentation version 2010 revised

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Database concepts presentation version 2010 revised

  1. 1. Created by M Nodalo, Port Moresby International School for Year 11 Information Technology (T) - ACT/BSSS, revised 2010
  2. 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. 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. 4. Stages of Processing Data Input processing Output data information• Calculating • Sorting • Classifying • Analysing • Summarising • reporting
  5. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 19. Field Name Data type Field size/length Description Sample database: Student file
  20. 20. Features of Computerised Databases  Create fields  Add and alter records  Search for specific records  Sort records  Print reports
  21. 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. 22. What is MS Access?  An example of a DBMS which was developed by Microsoft Corporation.
  23. 23. Database Terms in Access Fields (columns) Records (rows) table – refers to a file in Access
  24. 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. 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. 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. 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. 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. 29. Relational Database Relational database links some tables with certain data common with other tables.
  30. 30. Sources • Chapter 7 – Database Applications & Privacy Implications, Tomorrow’s Technology and You (8th ed) by G. Beekman & M. Quinn

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