Relational Model

Relational Database Systems

Following a famous paper written by Ted Codd in 1970, database systems changed considerably. Codd suggested that database systems should present the user with a view of data arranged as tables called relations.

Smaller and Smaller Systems

In the beginning, DBMS's were large, expensive software systems running on large computers. The size was compulsory, because to store a gigabyte of data required a large computer system.

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,

Database Programming

The following categories cover database programming. a) Relational Algebra b) The Database Language SQL c) Constraints and Triggers d) System Aspects of SQL e) Object-Orientation in Query Languages f) Logical Query Languages We start in category “Relational Algebra” with an abstract treatment of queries in the

Summary of The World of Database Systems

Database Management Systems: A DBMS is characterized by the capability to support efficient access to huge amounts of data, which persists over time. It is also characterized by support for powerful query languages and for durable transactions that can execute

The Entity-Relationship Data Model

The procedure to design a database starts with an analysis of what information the database must hold and what are the relationships among elements of that information. Often, the structure of the database, called the database schema, is specified in one of several

The Relational Data Model

While the entity-relationship approach to data modeling that we discussed in "The Entity-Relationship Data Model" is a simple and suitable way to explain the structure of data,

Tuples / Domains

The rows of a relation, other than the header row containing the attribute names, are called tuples. A tuple has one component for each attribute of the relation. For example, the first of the three

From E/R Diagrams to Relational Designs

We now consider the process by which a new database, such as our movie database, is created. We start with a design phase, in which we address and answer questions about what

Other Data Models

The entity-relationship and relational models are just two of the models that have importance in database systems today. In this section we shall introduce you to various other models of rising importance.

Page 0 of 2 « Previous 1 2 Next »