Chapter 9. Complex and legacy schemas
In this chapter
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Improving the SQL schema with custom DDL
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Integrating with a legacy database
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Mapping composite keys
In this chapter, we focus on the most important part of your system: the database schema, where your collection of integrity rules resides—the model of the real world that you’ve created. If your application can auction an item only once in the real world, your database schema should guarantee that. If an auction always has a starting price, your database model should include an appropriate constraint. If data satisfies all integrity rules, the data is consistent, a term you’ll meet again in section 11.1.
We also assume that consistent data is correct: everything the database states, ...
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