Flashcards

Normalisation

Fiona Faulkner A Level ICT A level Inglês 5 flashcards

Flashcards do conjunto (5)

1Give 2 characteristics of a table in 1NF (1st normal form)1)all data is atomic - cannot besplit up further, e.g. forename/surname
2)there is a primary key in the table
3)there is no repeating data, e.g. fields with the same data in 1 record
2Give 2 characteristics of a table in 2NF (2nd normal form)1)must be in 1NF
2)all non-key fields are dependent on the whole PK field(s)
3Give 3 charactersitics of a table in 3NF (3rd normal form)1)must be in 2NF
2)there is no functional dependency between non-key fields
4Give 3 advantages of normalisation1)removes redundant (repeated) data (data is only stored once)
2)less storage space needed to store database due to no repeated data
3)easier to add tables or fields to database in future
5Give 2 disadvantages of normalisation1)reduces database performance as more tables=longer to process queries
2)results of historical (old) calculations can't be stored

Descrição: A level A Level ICT FlashCards sobre Normalisation, criado por Fiona Faulkner em 14-05-2013.
Criado por: Fiona Faulkner · mai 2013
Atualizado: 11 mai 2016
Visualizações: 86
Tags: a level ict
Avaliação