Data independence is the ability to change the way data is organized and accessed without affecting the data itself. It is an important concept in database management systems (DBMSs) because it allows organizations to make changes to their databases without disrupting the users or applications that rely on the data.
There are two types of data independence:
Logical data independence:
This refers to the ability to change the logical structure of the database (i.e. the way data is organized and accessed) without affecting the way the data is used by applications. For example, an organization may want to change the way data is organized in a database from a hierarchical structure to a relational structure. With logical data independence, this change can be made without affecting the way applications access and use the data.
Physical data independence:
This refers to the ability to change the physical structure of the database (i.e. the way data is stored on disk) without affecting the logical structure of the database or the way the data is used by applications. For example, an organization may want to change the hardware or storage media used to store the data in a database. With physical data independence, this change can be made without affecting the way the data is organized and accessed.
Data independence is achieved through the use of a database management system (DBMS), which acts as an intermediary between the data and the users or applications that access the data. The DBMS handles the details of how the data is stored and accessed, allowing the users and applications to focus on the data itself.
Overall, data independence is an important characteristic of a DBMS, as it allows organizations to make changes to their databases without disrupting the users or applications that rely on the data.