Topic 8

Topic 8

1. Database

   • An organised collection of related data
   • It is possible to add, edit, manage and retrieve data from a database
   • The structure of a database allows data to be found and used quickly

2. Data Types

   • Number (integer)
   • Number (real)
   • Text or string
   • Date/time
   • Currency
   • Boolean
   • Lists
   • Picture
   • Sound
   • Video

3. Field

   • A single item of data within a record
   • Examples
     • surname: text
     • date of birth: date/time
     • selling price: currency

4. Record

   • consists of a collection of related files
   • Example
     • pupil's record in a school database only has the files related to that pupil (surname, forename, date of birth, from, etc.) and not another pupils data

5. File (table)

   • A collection of related fields
   • Example
     • The table of records of all pupils in the school

6. Key Fields (primary key)

   • Uniquely identifies each record
   • No two records have the same data on their key field
   • The purpose is to be able to refer to an individual record using a single field. This often takes the form of an identity number, membership number or bar code

7. Validation

   • Validation methods can only ensure reasonable and sensible data is input in to a system, but there is no certainty that the data is correct
   • Methods
     • Range Check
       • The data entered must be in a sensible range
     • Type Check
       • This ensures that the data is of the correct type
     • Format/Picture Check
       • If the data entered has a particular payttern, then an input mask can be used to force the data to conform to the rule.