Database Systems Study Guide (Chapters 1-4)

Comprehensive vocabulary flashcards covering basic definitions, architecture, ER modeling, and Enhanced ER modeling from the Chapters 1-4 study guide.

Database Management System (DBMS)

A software package/system to facilitate the creation and maintenance of a computerized database.

Database System

The combination of the database and the DBMS software.

Database Administrators (DBAs)

Individuals responsible for authorizing access to the database, coordinating and monitoring its use, and acquiring software and hardware resources.

Database Designers

Individuals responsible for identifying the data to be stored in the database and for choosing appropriate structures to represent and store this data.

Naïve / Parametric End Users

Users whose main job function revolves around constantly querying and updating the database, using standard types of queries and updates (called canned transactions).

Sophisticated End Users

Users who include engineers, scientists, business analysts, and others who thoroughly familiarize themselves with the facilities of the DBMS in order to implement their own applications to meet their complex requirements.

Standalone Users

Maintain personal databases by using ready-made program packages that provide easy-to-use menu-based or graphics-based interfaces.

Data Model

A collection of concepts that can be used to describe the structure of a database, providing the necessary means to achieve data abstraction.

Conceptual Data Models

High-level data models that provide concepts that are close to the way many users perceive data.

Physical Data Models

Low-level data models that provide concepts that describe the details of how data is stored on the computer storage media.

Database Schema

The description of a database which is specified during database design and is not expected to change frequently.

Database State (Instance)

The data in the database at a particular moment in time.

Three-Schema Architecture

An architecture with three levels: internal (describes physical storage), conceptual (describes structure for a community of users), and external (describes part of the database a user group is interested in).

Logical Data Independence

The capacity to change the conceptual schema without having to change external schemas or application programs.

Physical Data Independence

The capacity to change the internal schema without having to change the conceptual schema.

Data Definition Language (DDL)

The language used by the DBA and by database designers to define both the conceptual and internal schemas.

Data Manipulation Language (DML)

The language used for retrieval, insertion, deletion, and modification of the data.

Entity

A "thing" or "object" in the real world with an independent existence that is represented in the ER model.

Composite Attribute

An attribute that can be divided into smaller sub-parts, which represent more basic attributes with independent meanings.

Multi-valued Attribute

An attribute that can have a set of values for the same entity, such as colors for a car.

Derived Attribute

An attribute whose value is produced from another attribute or related entity (e.g., Age from Birthdate).

Key Attribute

An attribute of an entity type for which each particular entity has a unique value.

Weak Entity Types

Entity types that do not have key attributes of their own and are identified by being related to specific entities from another entity type.

Cardinality Ratio

Specifies the maximum number of relationship instances that an entity can participate in, such as $1:1$, $1:N$, or $M:N$.

Participation Constraint

Specifies whether the existence of an entity depends on its being related to another entity via the relationship type (Total vs. Partial).

Specialization

The process of defining a set of subclasses of an entity type (the superclass) based on some distinguishing characteristic (top-down).

Generalization

The process of identifying common features among several entity types and forming a broader superclass (bottom-up).

Disjointness Constraint

Specifies that the subclasses of a specialization must be disjoint, meaning an entity can be a member of at most one subclass.

Completeness Constraint

Specifies whether every entity in the superclass must be a member of at least one subclass in the specialization (Total vs. Partial).

Categories (UNION types)

A subclass that represents a collection of objects that is a subset of the union of entities from distinct entity types.

Aggregation

An EER abstraction that allows a relationship between entity types to be treated as a higher-level entity type.