Database Management Systems & Relational Data Modeling

Vocabulary practice flashcards covering basic terminology, models, keys, integrity constraints, and normalization concepts from lecture notes on database management systems.

Update Anomaly

An issue in computerized file-based systems where updating a single customer's address requires updating multiple entries.

Insertion Anomaly

An issue in file-based systems where you cannot insert information about a product until someone has purchased at least one unit of it.

Deletion Anomaly

An issue in file-based systems where removing a customer record causes the loss of product information if that customer was the only one who purchased the product.

Hierarchical Database Model

A database model based on parent-child relationships (1:M) where each record is linked to all of its child records.

Network Database Model

A database model created to improve on the hierarchical model by allowing records to have more than one parent and enabling data access from multiple points.

Relational Database Model

A model represented physically as a set of relations or tables storing data, where queries do not need to be known at design time and SQL specifies 'what' without 'how'.

Relation

A named two-dimensional grid or matrix of intersecting rows and columns that represents a set of tuples holding data about a set of objects.

Tuple

A row in a relational table, with each cell consisting of specific values for a particular variable or attribute.

Entity

A person, place, object, event, or concept in the user environment about which data is collected and stored.

Entity Type

A collection of entities that share common properties or characteristics.

Entity Instance

A single occurrence of an entity type.

Simple Attribute

An attribute that cannot be broken down into smaller components.

Composite Attribute

An attribute that can be broken down into its component parts.

Single-valued Attribute

An attribute that holds a single value for a given entity instance.

Multi-valued Attribute

An attribute that may take on more than one value for a given entity instance.

Derived Attribute

An attribute whose value can be derived from related attribute values.

Unary Relationship

A relationship of degree 1, also referred to as a recursive relationship or 'Bill of Materials'.

Degree of a Relationship

The number of entity types that participate in a specific relationship.

Cardinality

Specifies how many instances of one entity can (or must) be associated with each instance of another entity.

Associative Entity Type

An entity that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances.

Superkey

An attribute or combination of attributes that uniquely identifies each row in a table.

Candidate Key

A minimal, irreducible superkey.

Primary Key

A candidate key selected to uniquely identify rows in a table; it cannot contain NULL entries.

Foreign Key

An attribute or combination of attributes in one table whose values must either match the primary key in another table or be NULL.

Secondary Key

An attribute or combination of attributes used for data retrieval.

Entity Integrity

An integrity rule stating that every relation has a unique primary key, and the data values for all attributes in the primary key are not NULL.

Referential Integrity

An integrity rule stating that every non-NULL foreign key must reference an existing primary key value.

Normalization

A process first developed by E.F. Codd for evaluating and decomposing table structures to minimize data redundancies and reduce data anomalies.

Well-Structured Relation

A relation containing minimal data redundancy that allows users to insert, delete, and update rows without causing data inconsistencies.

First Normal Form (1NF)

The state of a relation in which all attribute values are atomic and it contains no multi-valued attributes.