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> For example, that your travel-agency application does not handle red-haired people.
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And in practice, many integrity constraints are actually guards to prevent "edge cases" reaching the application when the application can't handle them.
Typical example: every bank branch must have a postal address. Meaning: sorry, this application can't handle the travelling bank-in-a-bus that we introduced to serve remote rural communities. You're just going to have to give the bus a dummy address, or things won't work.
Michael Kay
Saxonica
