Three Level Architecture Schemas Mapping
Channel: Data Science Center
Date: 19/04/2020

Link between two level is establish by schema mapping.

Data item or object of one level interlink with the object of other level is called schema mapping
Two type of schema mapping

Conceptual Internal Mapping
Create link between external level and conceptual level. 
Specifies mapping between objects in the external view to those in the logical model. 

External Conceptual Mapping
Specifies mapping between objects in the logical model to those in the physical data model.