A link is a popular way to describe relationships in a relational database.
There are three types of relationships (links) between tables:
1. One-to-one relationship , that allows only one record on each side of the relationship.
2. One-to-many relationship, that allows a single record in one table to be related to multiple records in another table.
3. Many-to-many relationship, in which many records in a table can link to many records in another table. F