Developing a Conceptual Model › Identifying Relations › One-to-Many Relationship

One-to-Many Relationship

Example 1:

 Company

K  Company code

    Company name

    Company president

 Division

K       Company code

K   Division code

   Division name

   Division president

Example 2:

      Company

K  Customer code

   Customer name

   Customer type

   Customer credit limit

   Customer account balance

  Order

K    Order code

      Customer code

   Order quantity

  Order line

      Vendor ID

       Product code

To implement a many-to-many relationship between A and B:

• Create new entity C to contain the primary keys of A and B.
• Remove the relationship between A and B.
• Add a one-to-many relationship from A to C and B to C, where the primary keys of A and B compose the primary key for C.