Database Design

Database Design

"The Entity-Relationship Data Model" begins with a high-level notation for expressing database designs, called the entity-relationship model. We introduce in "The Relational Data Model" the relational model, which is the model used by the most widely adopted DBMS's, and which we touched upon briefly in "Relational Database Systems". We show how to translate entity-relationship designs into relational designs, or "relational database schemas." Later, in "Defining a Relation Schema in SQL", we show how to render relational database schemas formally in the data-definition portion of the SQL language.

“The Relational Data Model” also introduces the reader to the notion of "dependencies," which are formally stated assumptions about relationships among tuples in a relation. Dependencies allow us to improve relational database designs, through a process known as "normalization" of relations.

In "Other Data Models" we look at object-oriented approaches to database design. There, we cover the language ODL, which allows one to describe databases in a high-level, object-oriented fashion. We also look at ways in which object-oriented design has been combined with relational modeling, to yield the so-called "object-relational" model. Finally, "Other Data Models" also introduces "semistructured data" as an especially flexible database model, and we see its modern embodiment in the document language XML.




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