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Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
Database concepts presentation version 2010 revised
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Database concepts presentation version 2010 revised

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  • 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

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