Data Modeling - One-to-One Relationship (bijection)
1 - About
A one-to-one relationship describe that one row from a dataset point to exactly one row to the other dataset.
There are three way to model a one-to-one relationship:
- either the associated entities share the same primary keys values,
- a foreign key is held by one of the entities. This FK column should be constrained unique to simulate one-to-one multiplicity),
- or an association table is used to store the link between the 2 entities. A unique constraint has to be defined on each FK to ensure the one to one multiplicity.