Two cases must be considered:
The dependency relationships (DEP): the key of the SOURCE entity completes the key of the logical entity coming from the TARGET conceptual entity;
The linking relationships (non dependency): the key of the SOURCE entity is introduced as a redundant property into the logical entity coming from the TARGET conceptual entity.
The properties possibly held by the relationship are migrated into the logical entity coming from the TARGET conceptual entity.
Example: Dependency relationship
In the example, the conceptual entities, ORDER and ORDER_LINE, become logical entities.
The key of the entity ORDER (Order_No) is duplicated into the entity ORDER_LINE and completes the latter's key (Order_No + Line_No).
Example: Non dependency relationship
In the example, the conceptual entities, ORDER and CUSTOMER, become logical entities.
The key of the entity CUSTOMER (Customer_code) is duplicated into the entity ORDER as a property of this file.