Topic 8 - Databases

Topic 8 - Databases

1. Database

   • Is 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

3. Files, records and fields

   • A field is a single item of data within a record.
   • A record consists of a collection of related fields.
   • A file (Known as a table in Microsoft Access) is a collection of related fields

4. Key Field

   • A Key fields uniquely identities each record. No two records have the same data in their key field. Also known as Primary Key.
     • The purpose of the key field 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.

5. Validation

   • Data entered in to a database must be sensible or we get GIGO. 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.
     • Validation rules are needed for some fields. As data is entered it is checked to see that it obeys the rules; any data that does not obey the rules is not accepted. You can also set validation text – the text that appears if the data is not acceptable.

6. Reports

   • A report is a printed document that contains data from the database, organised and analysed in a certain way. A report from a student database might list the students in each class in alphabetical order.

7. Forms

   • Forms are used to make data entry more attractive and secure rather than entering data into raw tables.

8. Calculated fields

   • Not all data needed in a report may be present in a database. For example a person’s age is never included because it changes day by day. If you want to use age in a report it must be calculated. This result is known as a calculated field.

9. Uses of a database

   • Add, change or delete records
   • Search for a particular record
   • Sort the records into a given order
   • Print reports about some aspect of the database

10. Queries

    • A query specifies what records you are searching for and what fields from the records you would like to display.
      • Simple query search (keyword search) – looks for data in one field.
      • Complex query search – looks at data with multiple criteria.

11. Wildcards

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