5d Adv/Dis Of Normalisation ***

Question 0

Describe two advantages of normalisation. (4)

Answer 0

One mark for identification, second for exemplification/expansion eg: Reduced storage space (1) smaller hard drive required/less money spent on backup (1)
Increased data integrity (1) only one copy of the data kept and is correct (1) Data consistency (1) all data is the same and can be trusted to be correct (1) Data independence (1) queries/data access not dependent on software (1).

Question 1

Describe two disadvantages of normalisation. (4)

Answer 1

Limits data storage (1) calculated fields may need to be stored (1) Dos not store historical calculated data (1)
Increases number of tables (1) increases processing / memory requirements (1)
Fails to meet needs of airline (1) may want whole address as one not as single elements (1)

Question 2

The structure of the database has grown over time and is not fully normalised.
Describe two disadvantages of having a fully normalised database. (4)

Answer 2

Limits the data that can be stored (1) calculated fields may need
to be stored (1)
Increases number of tables (1) increases processing/
memory requirements/reduced database performance (1)
Fail to meet needs of company (1) may want whole address as one not as single elements (1)