Mapping 1:1 binary relationship types: There are three possible ways to be followed while mapping 1:1 binary relationship type R relating two entity types concept to relational design. One of the choices is foreign key approach where primary key of one of the entities is inserted to the other entity type’s relation as foreign key. Merging relation approach is valid when both entity types are total participated in R. This time, two different entity types are merged into one relation. As a third choice, a relationship is created where primary keys of two entity types are used as foreign keys. One of those foreign keys are chosen as primary key of R.