Databases

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Transcript

  • 1. Introduction to Databases
  • 2. Databases
    • A database is a collection of related pieces of information
    • A database can be computerised or non-computerised (manual - such as filing system, phone book etc.)
  • 3. Advantages of Computerised Databases
    • speed of information retrieval
    • storage capabilities
    • easy to update and delete
    • ease of access
    • multiple access
    • security
  • 4. Disadvantages of Computerised Databases
    • privacy and ethical issues
    • security risks
    • training of staff
    • initial expense (equipment, software)
    • software upgrades
  • 5. Terminology
    • A database or a table within a database is made of RECORDS
    • RECORDS contain information about a single item in the database/table.
    • Each record contains FIELDS .
    • A FIELD is a category of data that has been broken down into its simplest form.
      • Firstname, surname, street, suburb
  • 6. Terminology
    • In a database or table each ROW represents a record
    ID CDTitle Units In Stock Unit Price 1 Joe Cocker Essentials 3 $28.00 2 The Beatles 4 $35.00 3 Aussie Country Hits 2 $19.95
  • 7. Terminology
    • each COLUMN represents a field.
    . ID CDTitle Units In Stock Unit Price 1 Joe Cocker Essentials 3 $28.00 2 The Beatles 4 $35.00 3 Aussie Country Hits 2 $19.95
  • 8. Terminology
    • Every record in the same table has the same fields.
    • Databases are designed so that each data item is stored only once
  • 9. Terminology
    • The method of retrieving information from the database is known as QUERYING the database.
    • A query allows you to display a set of records which meet certain criteria
      • students in year 9
      • people with postcode 6192 etc.
  • 10. Terminology
    • Information taken from a database and designed for hardcopy (printout) is referred to as a REPORT .
    • Reports can be generated from tables or queries.
    • Reports can be formatted in many different styles depending on the target audience.
  • 11. Terminology
    • Other database operations include:
    • SEARCHING
      • locate the first record to contain some specific criteria
    • SORTING
      • sorting the database by a nominated field
  • 12. Terminology
    • Some database applications also provide a user friendly interface called a FORM .
    • Forms are used to display data from a table or query in an easy to read format.
  • 13. Planning a Database
    • Careful planning of a database before it is created will prove to be a useful exercise.
    • Step 1
    • Determine what data should be stored in each record.
    • Generate a list and eliminate information that is not directly related to the overall purpose of the database.
  • 14. Planning a Database
    • Step 2
    • What operations are to be performed on the database?
    • Do these operations require any missing information from the list?
    • Will there be any need to reduce the list further?
    • Adjust the list from step 1
  • 15. Planning a Database
    • Step 3
    • Create a list of fields and field names from step 2
    • Create a description of the data and their types (text, number, YES/NO etc)
    • Design a simple form for a single record on paper
  • 16. Planning a Database
    • Step 4
    • Create a new database/table using your software with the planned fields.
    • Enter the data into database