i) Data integration
- Integration of the data from several different systems into one database system which is shared by several users involves ensuring
- that there is no redundancy (or very little) of data.
- The aim is to have one database storing one logical item of data in one place which can be accessed by a range of information systems.
ii) Data abstraction
- Data abstraction is the process by which a database attempts to represent the properties of objects in the real world.
- A database records the relevant details required to support some organisational activity, it does not record all the details thus the database is an abstraction of the real world.
- The level of abstraction varies with different commercial databases.
iii) Data independence
- The aim is to achieve a situation where data organisation is transparent to the users or application programs which feed off the data.
- Thus, a change to some part of the physical database does not affect the application programs and also a change to the application programs does not affect the physical structure of the database.
- Physical and logical databases are independent.
iv) Data security
- To help ensure the integrity of the database, access to the database is restricted.
- Define a set of authorised users who have access to all or parts of the database.