Database

Database

1. Data Types are: number (integer), real number, string (text), Currency, Boolean, lists, picture, sound or video.

2. A 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.

3. Key Words for a database

   • A field is a single item of data contained within a record.
   • A record is a collection of related fields.
   • A table is a collection of related records and fields.
   • A key field uniquely identifies each record. Not two records have the same data in their key field. Also known as the primary key.

4. Validation methods

   • A range check checks that the data entered is within a sensible range.
   • A type check ensures that the data is of the correct type.
   • A format of picture check checks if the data entered has a particular pattern- (eg a postcode)
   • The length check ensures that the length of the input is checked for the number of characters used.
   • The presence check ensures that there is data in the required fields.
   • The look up list checks if the data entered consists of a limited number of possible entries then the computer can compare the entry with the list of allowed answers.

5. Forms are used to make data more attractive and secure rather than entering data in to raw tables.

   • A report is a printed document that contains data from the database. It is organised and analysed in a certain way. A report can be done in answer to a query.

6. Calculated fields: not all data is needed in a report may be present in a database. For example a person's age is never included because it changes every year.

7. Uses of a database: add, change or delete records; search for a particular record; sort the records given order; print reports about some aspects of the database.

8. Updating records: Records don't stay the same forever. They will need to be updated at some point. For example- people move house. The following can be done: add a new record when a pupil arrives at school; edit existing records when someone moves house; delete old records when people leave a school or job.

9. Searching for data: one main use of database is to find information quickly. To search you use a query.

   • Wildcard characters: you use a wildcard search when querying for data that you only know part of.

10. Sorting data: results of queries can be presented in a sorted order. - eg. alphabetical

    • Why sort data?- easier is lists are printed as reports; you can identify the best customer by amounts they have spent.

11. Security issues with databases: it cannot be destroyed, it cannot be accidently altered, it cannot go to unauthorised people.

12. Benefits of using a database: Fast access; easy to edit; validation; reports; sharing; security.