Explain data independence with its types.
Data independence is a concept in database management that refers to the ability to make changes to the database system without affecting its higher-level structures or applications. There are two main types of data independence:
Physical Data Independence:
Definition: Physical data independence allows modifications to the internal schema of the database without affecting the conceptual schema.
Explanation: This means you can change how the data is stored, reorganize files, add new access paths, or modify indexes without altering the way users or applications perceive and interact with the data at a higher level.
Example: Suppose you decide to reorganize the storage structure of a database for better performance by changing the way data is stored on disk. With physical data independence, you can make these changes without impacting how users or applications view and query the data.
Logical Data Independence:
Definition: Logical data independence allows modifications to the conceptual schema without affecting the external schemas or application programs.
Explanation: This means you can add or remove entities, modify relationships, or make changes to the overall structure of the database without requiring modifications to the external views or programs that interact with the data.
Example: Imagine you have a database with multiple applications accessing it. If you need to add a new entity or modify the structure of an existing one to better represent the business requirements, logical data independence ensures that these changes won’t disrupt the external views or programs using the data.