Conceptual vs. Actual Model of a Database
If we’re going to implement a data management application, we’ll probably need to design the database. First, we have to identify our business entities and map them to tables. Having identified the business entities, we then have to identify the relationships between these entities. These relationships can be any of the following:
One-to-one (1-1): One business entity is related to another single business entity.
One-to-many (1-n): One business entity is related to many other business entities.
Many-to-many (m-n): Many business entities are related to many other business entities.
Note: The type of relationship between two entities is also called “cardinality.”
Let’s look at the relationships with some examples.