Chapter 3: Data Models Vocabulary

A comprehensive set of vocabulary flashcards based on Chapter 3 lecture notes, covering data models, relationship types, business rules, and stages of database design.

Data Model

A representation, usually graphical, of a real-world data structure.

Data Modeling

The process of creating a specific data model for a problem to determine what data and relationships should be stored in the database.

Business Rule

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

Entity

A class of persons, places, objects, events, or concepts about which an organization needs to capture and store data, typically represented by a noun and a rectangle in notation.

Attribute

A characteristic, data field, or data element of an entity, such as a customer's name, address, or telephone number.

Relationship

An association between entities, typically represented by a verb and indicated by lines connecting entity boxes in a diagram.

Constraint

A restriction placed on data, often derived from business rules, such as a machine operator not working more than $10\,\text{hours}$ in any $24\text{-hour period}$.

Hierarchical Model

A data model based on an upside-down tree structure where a higher layer is the parent of the segment below (the child), and each child has only one parent.

Network Model

A data model created to represent complex relationships more effectively by allowing a record to have more than one parent.

Relational Model

A model implemented through an RDBMS where data and relationships are represented in a collection of two-dimensional tables called relations.

Schema

A standard database concept that emerged with the network model, defining the logical organization of the entire database.

Subschema

A concept from the network model defining the portion of the database seen by application programs.

Data Manipulation Language (DML)

A set of commands used to define the data environment and manage data within a database.

Data Definition Language (DDL)

A standard concept emerging from the network model used to define the database structure.

Table (Relation)

A two-dimensional structure composed of intersecting rows (records or tuples) and columns (attributes) that yields complete data and structural independence.

Relational Database Management System (RDBMS)

A sophisticated software system used to implement and manage the relational data model.

Structural Independence

The property where changes in the database structure do not affect the application program's ability to access the data.

Entity Relationship Model (ERM)

A widely accepted graphical tool for data modeling that provides a top-down representation of entities and their relationships.

Cardinality

The minimum and maximum number of entity occurrences associated with one occurrence of a related entity, established by specific business rules.

Crow's Foot Notation

A graphical representation used in ERDs to show the cardinality of relationships, using symbols for one, many, and zero instances.

One-to-One ($1:1$)

A relationship type where one instance of an entity is associated with exactly one instance of another entity, such as a Driver and a Truck.

One-to-Many ($1:M$)

A relationship type where one instance of an entity (the parent) is associated with many instances of another entity (the child).

Many-to-Many ($M:N$)

A relationship where instances on both sides can occur more than once, commonly resolved into two $1:M$ relationships in a relational environment.

Associative Entity

Also known as a weak entity, it is used to resolve $M:N$ relationships and is composed of the primary keys of the entities it connects.

Unary Relationship

A relationship degree where an association is maintained within a single entity, such as an Employee who manages other Employees.

Binary Relationship

A relationship degree involving the association of exactly two distinct entities.

Ternary Relationship

A relationship degree involving the association of three distinct entities, such as Doctor, Patient, and Drug.

Object-Oriented Data Model (OODM)

A model where both data and its relationships are contained in a single structure known as an object.

Encapsulation

Incorporating both data and functions into a single unit where they are protected from modification from outside the unit.

Inheritance

The ability of an object within a class hierarchy to inherit the attributes and methods of classes above it.

Unified Modeling Language (UML)

A language based on OO concepts that provides a set of diagrams and symbols for graphically modeling a system.

Physical Level (Internal Level)

The lowest level of data abstraction where raw data is stored in file format on physical hard drives.

Logical Level (Conceptual Level)

The level of data abstraction where raw data is organized into a proper structure, such as a tabular format.

View Level (External Level)

The level of data abstraction where end users see data based on queries, presented in formats like tables, graphs, or pie charts.

Conceptual Data Model

A model identifying highest-level relationships between entities without specifying attributes or primary keys, focusing on a bird's eye view.

Software Independence

A characteristic of a model where it does not depend on the specific DBMS software used for implementation.

Hardware Independence

A characteristic of a model where it does not depend on the specific hardware used in the database implementation.

Data Dictionary

A detailed description of all tables in the database, containing attribute names and characteristics, essentially documenting the metadata.

Metadata

Data about data.

NoSQL

A non-relational database model suited for Big Data, based on a schema-less key-value model for large sparse data stores.