# Data Independence

## Data Independence

* Data independence is explained using the three-schema architecture.
* It is the characteristic of being able to modify the schema at one level of the database system without altering the schema at the next higher level.

## Data Independence Classification

* Logical Data Independence
* Physical Data Independence

## Logical Data Independence

* It is the capacity to change the conceptual schema without having to change the external schema.
* It separates the external level from the conceptual level.
* Any changes in the conceptual view of the data would not affect the user view of the data.
* Logical data independence occurs at the user interface level.

## Physical Data Independence

* It is the capacity to change the internal schema without having to change the conceptual schema.
* Any changes in storage size of the database system server would not affect the conceptual structure of the database.
* It separates conceptual levels from the internal level.
* Physical data independence occurs at the logical interface level.