Domain Constraints

A domain is the set of logically related values from which the value in a particular column can be drawn. Here are some examples of domains in the bookbiz database:

  • The domain of the authors.au_id column is all the Social Security numbers issued by the U.S. government.

  • The domain of the authors.city and publishers.city columns is all the cities in the United States; for authors.state and publishers. state, it's all the states in the United States. (Note the assumption that all authors live in the United States.)

  • The domain of titles.type is the following set of values: business, popular_comp, psychology, mod_cook, and trad_cook.

  • The domain of titles.title_id is the set of values with the following format: The first two characters ...

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