Chapter 3: Data modeling

aggregation relationship

aggregation relationship

A special-purpose UML notation representing the relationship between two classes that are often considered together, such as when a sports league is made up of a collection of teams.

association

UML symbol that depicts the relationship between two classes; it is modeled as a solid line that connects two classes in a model.

attributes

Data elements that describe instances in a class, very much like fields in a database table; characteristics, properties, or adjectives that describe each class.

business rule

Succinct statements of constraints on business processes; they provide the logic that guides the behavior of the business in specific situations.

class

Any separately identifiable collection of things (objects) about which the organization wants to collect and store information.

can represent organization resources (e.g., trucks, machines, buildings, cash, investments), persons (e.g., customers, employees), events (e.g., sales, purchases, cash disbursements, cash receipts), and conceptual structures (e.g., accounts, product categories, budgets).

are typically implemented as tables in a relational database, where individual instances of the class are represented as rows in the table.

class diagrams

Structure models prepared using UML notation.

composition relationship

A special-purpose UML notation representing the relationship between two classes that are often considered together, similar to aggregation relationships, except in composition relationships, one class cannot exist without the other, such as a book and the chapters that compose the book.

constraints

Optional or mandatory guidance about how a process should perform in certain situations.

data models

A graphic representation of the conceptual contents of databases; data models support communication about database contents between users and designers of the database.

entities

The people, things, and events in the domain of interest; in UML notation, entities are modeled as classes.

foreign key (FK)

Attribute that allows database tables to be linked together; foreign keys are the primary keys of other tables placed in the current table to support the link between the two tables.

generalization relationship

A special-purpose UML symbol that supports grouping of things that share common characteristics; it reduces redundancy because the shared characteristics need only be modeled once.

multiplicities , (cardinalities)

UML symbols that describe the minimum and maximum number of times an instance of one class can be associated with instances of another class for a specific association between those two classes; they indicate whether the two classes are part of one-to-one, one-to-many, or many-to-many relationships.

primary key (PK)

An attribute or a combination of attributes that uniquely identifies an instance of a class in a data model or a specific row in a table.

relationship

The business purpose for the association between two classes or two database tables; see association.

structure model

A conceptual depiction of a database, such as a UML class model or an entity-relationship model.