BCA - Data Manipulation and Analysis (DMA)

Logical Data Independence:
The ability to change the conceptual schema without affecting external schemas or application programmes is known as logical data independence.
Additions or deletions of new entities, properties, or relationships in the conceptual schema should be possible without requiring changes to existing external schemas or rewriting application programmes.

Physical Data Independence:
Physical data independence is the ability to modify the inner schema without having alteration to the conceptual schemas or application programs. Alteration in the internal schema might include.
* Using new storage devices.
* Using different data structures.
* Switching from one access method to another.
* Using different file organizations or storage structures.
* Modifying indexes.