34.19. How to Represent Relationships in Tables

The code in the prior section relies on a MANU_OID foreign key in the PRODUCT_SPEC table to link to a record in the MANUFACTURER table. This highlights the question: How are object relationships represented in the relational model?

The answer is given in the Representing Object Relationships as Tables pattern {BW96], which proposes the following:

  • one-to-one associations

    • Place an OID foreign key in one or both tables representing the objects in relationship.

    • Or, create an associative table that records the OIDs of each object in relationship.

  • one-to-many associations, such as a collection

    • Create an associative table that records the OIDs of each object in relationship.

  • many-to-many associations

    • Create ...

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