Principles of Database Systems - Data Models & Entity Relationship Model

Vocabulary flashcards covering core concepts of database design, data models, schema architectures, DBMS languages, and the Entity Relationship Model from Lecture 2.

Requirements and Specification

The database design phase that involves scoping out the requirements and limitations of the database.

Conceptual Design

The database design phase involving the use of a data model (e.g. Entity Relationship Model) to represent the requirements of the specifications.

Logical Design

The database design phase that involves translating the conceptual design into tables and relationships expressed in a data model and implemented in a DBMS.

Data Model

A relatively simple representation using graphics of facts (data) used to describe real world events, objects, or ideas.

Database Model

A collection of logical constructs based on a data model used to represent data structure and data relationships found within a specific database.

Entity

A component of a data model structure that represents an object of interest to a user, describing an object in the real world.

Attribute

Characteristics that describe an entity in a data model structure.

Constraint

A restriction placed on data within a data model structure, such as numeric value bounds or operational limits.

Business Rule

A brief, precise, and unambiguous description of a policy, procedure, or principle within an organization.

Conceptual Data Model

A high-level semantic data model providing concepts that are close to the way many users perceive data.

Physical Data Model

A low-level internal data model providing concepts that describe details of how data is stored in the computer.

Implementation Data Model

A representational data model providing concepts that fall between conceptual and physical models, used by many commercial DBMS implementations.

Database Schema

The logical view of a database (also called intension) that defines table structures, relationships, and constraints, changing very infrequently.

Database State

The actual data stored in a database at a particular moment in time (also called database instance, snapshot, or extension), changing with every update.

Three-Schema Architecture

An architectural framework that defines database schemas at three levels (external, conceptual, internal) to support program-data independence and multiple user views.

Logical Data Independence

The capacity to change the conceptual schema without having to change the external schemas and their associated application programs.

Physical Data Independence

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

Data Definition Language (DDL)

Language used by DBAs and database designers to specify the conceptual, internal, and external schemas of a database.

Data Manipulation Language (DML)

Language used to specify database retrievals and updates, which can be procedural or non-procedural.

High-Level (Non-procedural) DML

A set-oriented declarative language, such as SQL, that specifies what data to retrieve rather than how to retrieve it.

Low-Level (Procedural) DML

A language that retrieves data one record at a time using constructs like loops and positioning pointers, embedded in host languages.

Network Model

A database model represented as graphs where object types are nodes and relationships are arcs, using navigational constructs like FIND and GET.

Hierarchical Model

A database model where data is stored in a tree-like structure of connected parent and child records, traversed from the root node.

Relational Model

A database model proposed in 1970 by E.F. Codd that promotes structural independence using independent tables and ad hoc SQL query capability.

Entity Relationship Model (ERM)

A database model that uses graphical representations (ERDs) to model entities, attributes, and relationships.

Internal Model Translation

The process of mapping conceptual ERD entities and relationships into explicit SQL DDL CREATE TABLE statements in a DBMS.