Topic 8

Topic 8

1. database-is an organised collection of related data.

2. Data Types

   • text or string
   • currecy
   • Boolean
   • number
   • picture
   • sound
   • lists

3. what is a field?

   • a single item of data within a record

4. what is a record?

   • consists of a collection of related files

5. what is a file?

   • is a collection of related files

6. a key fields uniquely identifies each record

   • for example a Pupil ID

7. data entered into a database must be sensible or we get gigo

   • 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:ifthe data entered has a particular pattern then an input mask can be used to force the data to conform
   • length check: the length of the input is checked for the number of characters used.
   • presence check: some data has to be entered
   • lookup list:if the data entered consists of a limited number of possible entries then the computer can compare the entry with a list of allowed answers.

8. 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

9. simple query search-looks for data in one field

10. complex query search-looks at data with multiple criteria

11. results of queries can be presented in a sorted order

12. methods of keeping data secure are : passwords,back ups and access rights