Data independence

Definition :- Data independence is allows the database to structure changed. It means data can be add, deleted or data attributes altered with disruption to a existing system.

data

Two level of data independence are:

  • Logical data independence :- Insulates application program from logical operations such as combining two records into one or splitting an existing record into two or more records.
  • Physical data independence :- indicates that the physical storing structures or devices used for storing data could be change without needing a change in the records structure or application program.

Logical data independence

  1. Logical data is concerned with a structure of data.
  2. Logical data is very difficult as the retrieving of data is dependent on the logical structure of data.
  3. Application program need not be changed if new field is added or deleted from the database.

Physical data independence

  1. Physical data is concerned with storage of data.
  2. Physical data is easy to retrieve.
  3. It is concerned with the change of the storage device.