Modern Database Management - Chapter 2 Vocabulary

Flashcards covering key vocabulary from the Modern Database Management lecture.

Entity Instance

Person, place, object, event, or concept; often corresponds to a row in a table.

Entity Type

Collection of entities that share common properties; often corresponds to a table.

Relationship Instance

Link between entities; corresponds to primary key-foreign key equivalencies in related tables.

Relationship Type

Category of relationship; link between entity types.

Attributes

Properties or characteristics of an entity or relationship type; often corresponds to a field in a table.

Business Rules

Statements that define or constrain some aspect of the business.

Declarative Business Rule

States what should be, not how it should be done.

Atomic Business Rule

A business rule that makes one statement.

Data Definition

Explanation of a term or fact within the data.

Term

Word or phrase with a specific meaning related to data.

Fact

Association between two or more terms.

Entity

A person, place, object, event, or concept in the user environment about which the organization wishes to maintain data.

Strong Entity

Exists independently of other types of entities and has its own unique identifier.

Weak Entity

Dependent on a strong entity (identifying owner) and cannot exist on its own; does not have a unique identifier.

Identifying Relationship

Links strong entities to weak entities.

Attribute

Property or characteristic of an entity or relationship type.

Required Attribute

Must have a value for every entity instance.

Optional Attribute

May not have a value for every entity instance.

Composite Attribute

An attribute that has meaningful component parts (sub-attributes).

Multivalued Attribute

May take on more than one value for a given entity instance.

Derived Attribute

Values can be calculated from related attribute values and are not physically stored in the database.

Identifier (Key)

An attribute (or combination of attributes) that uniquely identifies individual instances of an entity type.

Candidate Identifier

An attribute that could be an identifier because it satisfies the requirements for being an identifier.

Relationship Type

The relationship between entity types.

Relationship Instance

The relationship between specific entity instances.

Associative Entity

Combination of relationship and entity; used to represent many-to-many relationships and can have its own attributes.

Unary Relationship

Entities of the same entity type related to each other.

Binary Relationship

Entities of one type related to entities of another type.

Ternary Relationship

Entities of three different types involved in the same relationship.

One-to-One Cardinality

Each entity in the relationship will have exactly one related entity.

One-to-Many Cardinality

An entity on one side of the relationship can have many related entities, but an entity on the other side will have a maximum of one related entity.

Many-to-Many Cardinality

Entities on both sides of the relationship can have many related entities on the other side.

Cardinality Constraints

The number of instances of one entity that can or must be associated with each instance of another entity.

Minimum Cardinality

If zero, then optional; if one or more, then mandatory.

Maximum Cardinality

The maximum number of instances that can be related.

Time Stamp

A time value that is associated with a data value, often indicating when some event occurred that affected the data value.