Following are the types of object-relational mapping :
One-to-one mapping : The one-to-one mapping represents a single-valued association where an instance of one entity is associated with an instance of another entity. In this type of association, one instance of source entity can be mapped with at most one instance of the target entity.
One-To-Many mapping : The One-To-Many mapping comes into the category of collection-valued association where an entity is associated with a collection of other entities. In this type of association, the instance of one entity can be mapped with any number of instances of another entity.
Many-to-one mapping : The Many-To-One mapping represents a single-valued association where a collection of entities can be associated with the similar entity. In the relational database, more than one row of an entity can refer to the same row of another entity.
Many-to-many mapping : The Many-To-Many mapping represents a collection-valued association where any number of entities can be associated with a collection of other entities. In the relational database, more than one row of one entity can refer to more than one row of another entity.
