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.

Multimedia Data

One of the important trends in database systems is the addition of multimedia data. By multimedia" we mean information that represents a signal of some sort. Common types of multimedia data include video, audio, radar signals, satellite images, and documents or pictures in different encodings.

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 System Implementation

The subject of database system implementation can be divided roughly into three parts: 1. Storage management: how secondary storage is used effectively to hold data and allow it to be accessed quickly.

Multiway Relationships

The E/R model makes it easy to describe relationships involving more than two entity sets. In practice, ternary (three-way) or higher-degree relationships are infrequent, but they are rarely necessary to reflect the true state of affairs. A multiway relationship in an E/R diagram

Converting Multiway Relationships to Binary

There are a number of data models, such as ODL (Object Definition Language), which we introduce in Introduction to ODL, that limit relationships to be binary. Therefore, while the E/R model does not require binary relationships,

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

Equivalent Representations of a Relation

Relations are sets of tuples, not lists of tuples. Therefore the order in which the tuples of a relation are presented is unimportant. For instance, we can list the three tuples of the

Relation Instances

A relation about movies is not stationary; rather, relations change over time. We expect that these changes include the tuples of the relation, such as insertion of new tuples as movies

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

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