An Introduction to Relationships

Three types of relationships can exist between tables in a database: one-to-many, one-to-one, and many-to-many. Setting up the proper type of relationship between two tables in your database is imperative. The right type of relationship between two tables ensures:

  • Data integrity

  • Optimal performance

  • Ease of use in designing system objects

This chapter discusses many reasons behind these benefits. Before you can understand the benefits of relationships, though, you must understand the types of relationships available.


A one-to-many relationship is by far the most common type of relationship. In a one-to-many relationship, a record in one table can have many related records in another table. A common example ...

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