(CST 225) Database Management Chapter 1

Chapter 1

Design Phases of Database

Development process that includes requirements gathering, conceptual design, logical design, and physical design.

Design Issues

Redundancy and integrity constraints in database management.

The E-R Model

A data modeling technique for representing entities, their attributes, and relationships in a database.

Entity Sets

Collections of similar objects that represent entities in a database, shared by the same attributes.

Attributes

Properties or characteristics of an entity that define its data in a database.

Relationship Sets

Groups of relationships that share the same connections between entities in a database.

Composite Attributes

Attributes that can be broken down into smaller sub-parts, representing more detailed information.

Complex Attributes

Attributes that can be broken down into smaller sub-attributes, detailing more specific information within a database.

Derived Attribute

An attribute whose value is calculated from other attributes rather than stored directly in the database.

Multi-Valued Attribute

An attribute that can hold multiple values for a single entity, such as phone numbers or email addresses.

Strong Entity Set

An entity set that has a primary key and can exist independently in the database. Strong entities are typically represented by a solid rectangle in an entity-relationship diagram.

Weak Entity Set

An entity that cannot be uniquely identified by its own attributes alone and relies on a strong entity to provide part of its primary key.

Strong Relationship

A relationship that uniquely connects strong entities, typically represented by a diamond in an entity-relationship diagram, indicating that the participating entities have their own primary keys.

Weak Relationship

A relationship that connects weak entities to strong entities, where weak entities lack a full primary key and depend on the strong entity for identification.

Recursive Relationship

A relationship in which an entity is related to itself, allowing for hierarchical data structures and representing connections within the same entity set.

Ternary Relationship

A relationship involving three entities that simultaneously participate in the relationship, where each entity contributes to the association.

Cardinality Ratio

The cardinality ratio describes the numerical relationship between entities in a relationship, indicating the minimum and maximum number of instances of one entity that can be associated with instances of another entity.

One to One Cardinality

A type of cardinality where each instance of one entity is associated with exactly one instance of another entity, and vice versa.

One to Many Cardinality

A type of cardinality where a single instance of one entity can be associated with multiple instances of another entity, but each instance of the second entity is associated with only one instance of the first entity.

Many to One Cardinality

A type of cardinality where multiple instances of one entity can be associated with a single instance of another entity, but that instance of the second entity is associated with only one instance of the first entity.

Many to Many Cardinality

A type of cardinality where multiple instances of one entity can be associated with multiple instances of another entity, allowing for many-to-many relationships.

Total Participation

A type of participation in which all instances of an entity are involved in a relationship, ensuring that every instance is represented in the relationship.

Partial Participation

A type of participation in which some instances of an entity may be involved in a relationship, but not all instances are required to be represented.

Disjointedness Constraint

A constraint that specifies that two or more entities cannot share the same instance in a relationship, ensuring that each instance is unique to a specific entity.

Overlap Constraint

A constraint that allows instances of two or more entities to share the same instance in a relationship, permitting overlapping participation among entities.

Completeness Constraint

A constraint that dictates whether all instances of an entity must participate in a relationship, either fully or partially, ensuring that none are left out.

Total Specialization Constraint

A constraint that requires every instance of a specific entity type to be a member of at least one subtype, establishing a complete hierarchy of specialization.

Partial Specialization

A constraint that permits some instances of a specific entity type to not belong to any subtype, allowing for incomplete hierarchies of specialization.

Aggregation

A concept in database management that allows a relationship between a collection of entities and another entity, effectively treating the collection as a single higher-level entity.