DATA INDEPENDENCE in DBMS

DATA INDEPENDENCE:

•  A very important advantage of using DBMS is that it offers Data Independence. 
• The ability to modify a scheme definition in one level without affecting a scheme definition in a higher level is called data independence.

•  There are two kinds:

         1. Physical Data Independence 
        2. Logical Data Independence 

Physical Data Independence: 

• The ability to modify the physical schema without causing application programs to be rewritten  

• Modifications at this level are usually to improve performance. 

Logical Data Independence:

•  The ability to modify the conceptual schema without causing application programs to be rewritten
•  Usually done when logical structure of database is altered 
• Logical data independence is harder to achieve as the application programs are usually heavily dependent on the logical structure of the data.