Type Inheritance and Relational Theory: Subtypes, Supertypes, and Substitutability 1st Edition

Type inheritance is that phenomenon according to which we can say, for example, that every square is also a rectangle, properties and so that apply to rectangles in general apply to squares in particular. In other words, squares are a subtype of rectangles, and rectangles are a supertype of squares. Визнаючи проектів житлового and acting upon such subtype / supertype relationships provides numerous benefits: Certainly it can help in data modeling, and it can also provide for code reuse in applications. For these reasons, many languages, including the database standard language SQL, have long supported such relationships. However, there doesn't seem to be any consensus in the community at large on a formal, rigorous, and model of abstract inheritance. This book proposes such a model one that enjoys several advantages over other approaches, not the least of which it is that it's fully compatible with the well known relational model of data.