Data independence is a different term which represents the usage of the three-schema architecture. It refers to the character trait of being capable of modifying the schema at one level of the database system. It occurs without changing the schema at the next level.
Data independence is of two types:
1. Logical Data Independence
Logical data independence is a characteristic feature of being able to alter the conceptual schema. It occurs without having a necessity to modify the external schema. This type of autonomy is useful for separating the external level from the theoretical point of view. If we perform any alterations in the conceptual perspective of the data, then the user perspective of the data will be safe from being affected. Logical data independence always occurs at the level of the user interface.
2. Physical Data Independence
Physical data independence represents the capacity to alter the internal schema without having any change in the conceptual schema of the data. If we perform any changes in the storage size of the database system server, then the database, including the logical structure, will not face any change. It is useful in separating the conceptual levels and differentiating them from the internal standards. It occurs at the level of the logical interface.