WGU - Data Management Foundations

Ad hoc query

A spur-of-the-moment question.

Analytical database

A database focused primarily on storing historical data and business metrics used for tactical or strategic decision making.

Centralized database

A database located at a single site.

Cloud database

A database that is created and maintained using cloud services, such as Azure or AWS.

Data

Raw facts, or facts that have not yet been processed to reveal their meaning to the end user.

Data anomaly

A data abnormality in which inconsistent changes have been made to a database. For example, an employee moves, but the address change is not corrected in all files in the database.

Data dependence

A data condition in which data representation and manipulation are dependent on the physical data storage characteristics.

Data dictionary

A DBMS component that stores metadata - data about data. Thus, the data dictionary contains the data definition as well as their characteristics and relationships. A data dictionary may also include data that are external to the DBMS. Also known as an information resource dictionary.

Data inconsistency

A condition in which different versions of the same data yield different results.

Data independence

A condition in which data access is unaffected by changes in the physical data storage characteristics.

Data integrity

In a relational database, a condition in which data in the database compiles with all entity and referential integrity constraints.

Data management

A process that focuses on data collection, storage, and retrieval. Common data management functions include addition, deletion, modification, and listing.

Database system

An organization of components that defines and regulates the collection, storage, management, and use of data in a database environment.

Desktop database

A single-user database that runs on a personal computer.

Field

An alphabetic or numeric character or group of characters that defines a characteristic of a person, place, or thing. For example, a person's Social Security number, address, phone number, and bank balance are all constitute fields.

File

A named collection of related records.

General-purpose databases

A database that contains a wide variety of data used in multiple disciplines.

Hub

A warehouse of data packets housed in a central location on a local area network. It contains multiple ports that copy the data in the data packets to make it accessible to selected or all segments of the network.

Information

The result of processing raw data to reveal its meaning. Information consists of transformed data and facilitates decision making.

Knowledge

The body of information and facts about a specific subject. Knowledge implies familiarity, awareness, and understanding of information as it applies to an environment. A key characteristic is that new knowledge can be derived from old knowledge.

Online analytical processing (OLAP)

Decision support system (DSS) tools that use multidimensional data analysis techniques. OLAP creates an advanced data analysis environment that supports decision making, business modeling, and operations research.

Operational database

A database designed to primarily support a company's day-to-day operations. Also known as a transactional database, OLTP database, or production database.

Record

A collection of related (logically connected) fields.

Semistructured data

Data that has already been processed to some extent.

Structural dependence

A data characteristic in which a change in the database schema affects data access, thus requiring changes in all access programs.

Structural independence

A data characteristic in which changes in the database schema do not affect data access.

Structured data

Data that has been formatted to facilitate storage, use, and information generation.

Unstructured data

Data that exists in its original, raw state; that is, in the format in which it was collected.

Workgroup database

A multiuser database that usually supports fewer than 50 users or is used for a specific department in an organization.

XML database

A database system that stores and manages semistructured XML data.

Abstract data type (ADT)

Data type that describes a set of similar objects with shared and encapsulated data representation and methods. An abstract data type is generally used to describe complex objects.

Application programming interface (API)

Software through which programmers interact with middleware. An API allows the use of generic SQL code, thereby allowing client processes to be database server-independent.

Attribute

A characteristic of an entity or object. An attribute has a name and a data type.

Class

A collection of similar objects with shared structure (attributes) and behavior (methods). A class encapsulates an object's data representation and a method's implementation. Classes are organized in a class hierarchy.

Class hierarchy

The organization of classes in a hierarchical tree in which each parent class is a superclass and each child class is a subclass.

Constraint

A restriction placed on data, usually expressed in the form of rules. For example, "A student's GPA must be between 0.00 and 4.00." Constraints are important because they help to ensure data integrity.

Data definition language (DDL)

The language that allows a database administrator to define the database structure, schema, and subschema.

Data manipulation language (DML)

The set of commands that allows an end user to manipulate the data in the database, such as SELECT, INSERT, UPDATE, DELETE, COMMIT, and ROLLBACK.

Entity

A person, place, thing, concept, or event for which data can be stored.

Entity instance

A row in a relational table. Also known as entity occurrence.

Eventual consistency

A model for database consistency in which updates to the database will propagate through the system so that all data copies will be consistent eventually.

Hardware independence

A condition in which a model does not depend on the hardware used in the model's implementation. Therefore, changes in the hardware will have no effect on the database design at the conceptual level.

Inheritance

In the object-oriented data model, the ability of an object to inherit the data structure and methods of the classes above it in the class hierarchy.

Internal model

In database modeling, a level of data abstraction that adapts the conceptual model to a specific DBMS model for implementation. The internal model is the representation of a database as "seen" by the DBMS. In other words, the internal model requires a designer to match the conceptual model's characteristics and constraints to those of the selected implementation model.

Key-value

A data model based on a structure composed of two data elements: a key and a value, in which every key has a corresponding value or set of values. The key-value data model is also called the associative or attribute-value data model.

Many-to-many (M:N or ..) relationship

Association among two or more entities in which one occurrence of an entity is associated with many occurrences of a related entity and one occurrence of the related entity is associated with many occurrences of the first entity.

Object

An abstract representation of a real world entity that has a unique identity, embedded properties, and the ability to interact with other objects and itself.

object-oriented data model (OODM)

A data model whose basic modeling structure is an object.

object-oriented database management system (OODBMS)

Data management software used to manage data in an object-oriented database model.

object/relational database management system (O/R DBMS)

A DBMS based on the extended relational model (ERDM). The ERDM, championed by many relational database researchers, constitutes the relational model's response to the OODM. This model includes many of the object-oriented model's best features within an inherently simpler relational database structure.

one-to-many (1:M or 1..*) relationship

Associations among two or more entities that are used by data models. In a 1:M relationship, one entity instance is associated with many instances of the related entity.

one-to-one (1:1 or 1..1) relationship

Associations among two or more entities that are used by data models. In a 1:1 relationship, one entity instance is associated with only one instance of the related entity.

relation

A logical construct perceived to be a two dimensional structure composed of intersecting rows (entities) and columns (attributes) that represents an entity set in the relational model.

relational database management system (RDBMS)

A collection of programs that manages a relational database. The RDBMS software translates a user's logical requests (queries) into commands that physically locate and retrieve the requested data.

relationship

An association between entities.

schema

A logical grouping of database objects, such as tables, indexes, views, and queries, that are related to each other. Usually, a schema belongs to a single user or application.

subschema

The portion of the database that interacts with application programs.

superclass

In a class hierarchy, the superclass is the more general classification from which the subclasses inherit data structures and behaviors.

table

A logical construct perceived to be a two dimensional structure composed of intersecting rows (entities) and columns (attributes) that represents an entity set in the relational model.

tuple

In the relational model, a table row.

versioning

A property of an OODBMS that allows the database to keep track of the different transformations performed on an object.

candidate key

A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a superkey.

composite entity

An entity designed to transform an M:N relationship into two 1:M relationships. The composite entity's primary key comprises at least the primary keys of the entities that it connects. Also known as a bridge entity or associative entity.

composite key

A multiple-attribute key.

determination

The role of a key. In the context of a database table, the statement "A determines B" indicates that knowing the value of attribute A means that the value of attribute B can be looked up.

domain

In data modeling, the construct used to organize and describe an attribute's set of possible values.

entity integrity

The property of a relational table that guarantees each entity has a unique value in a primary key and that the key has no null values.

flags

Special codes implemented by designers to trigger a required response, alert end users to specified conditions, or encode values. Flags may be used to prevent nulls by bringing attention to the absence of a value in a table.

foreign key (FK)

An attribute or attributes in one table whose values must match the primary key in another table or whose values must be null.

full functional dependence

A condition in which an attribute is functionally dependent on a composite key but not on any subset of the key.

functional dependence

Within a relation R, an attribute B is functionally dependent on an attribute A if and only if a given value of attribute A determines exactly one value of attribute B. The relationship "B is dependent on A" is equivalent to "A determines B," and is written as A B.

index

An ordered array of index key values and row ID values (pointers). Indexes are generally used to speed up and facilitate data retrieval. Also known as an index key.

key attribute

The attributes that form a primary key.

linking table

In the relational model, a table that implements an M:M relationship.

null

The absence of an attribute value. Note that a null is not a blank.

predicate logic

Used extensively in mathematics to provide a framework in which an assertion (statement of fact) can be verified as either true or false.

primary key (PK)

In the relational model, an identifier composed of one or more attributes that uniquely identifies a row. Also, a candidate key selected as a unique entity identifier.

prime attribute

A key attribute; that is, an attribute that is part of a key or is the whole key.

referential integrity

A condition by which a dependent table's foreign key must have either a null entry or a matching entry in the related table.

secondary key

A key used strictly for data retrieval purposes. For example, customers are not likely to know their customer number (primary key), but the combination of last name, first name, middle initial, and telephone number will probably match the appropriate table row.

set theory

A part of mathematical science that deals with sets, or groups of things, and is used as the basis for data manipulation in the relational model.

superkey

An attribute or attributes that uniquely identify each entity in a table.

unique index

An index in which the index key can have only one associated pointer value (row).

binary relationship

An ER term for an association (relationship) between two entities. For example, PROFESSOR teaches CLASS.

cardinality

A property that assigns a specific value to connectivity and expresses the range of allowed entity occurrences associated with a single occurrence of the related entity.

composite attribute

An attribute that can be further subdivided to yield additional attributes. For example, a phone number such as 615-898-2368 may be divided into an area code (615), an exchange number (898), and a four-digit code (2368). Compare to simple attribute.

composite identifier

In ER modeling, a key composed of more than one attribute.

derived attribute

An attribute that does not physically exist within the entity and is derived via an algorithm. For example, the Age attribute might be derived by subtracting the birth date from the current date.

existence-dependent

A property of an entity whose existence depends on one or more other entities. In such an environment, the existence-independent table must be created and loaded first because the existence-dependent key cannot reference a table that does not yet exist.

existence-independent

A property of an entity that can exist apart from one or more related entities. Such a table must be created first when referencing an existence-dependent table.

identifiers

One or more attributes that uniquely identify each entity instance.

iterative process

A process based on repetition of steps and procedures.

mandatory participation

A relationship in which one entity occurrence must have a corresponding occurrence in another entity. For example, an EMPLOYEE works in a DIVISION. (A person cannot be an employee without being assigned to a company's division.)

multivalued attributes

An attribute that can have many values for a single entity occurrence. For example, an EMP_DEGREE attribute might store the string "BBA, MBA, PHD" to indicate three different degrees held.

non-identifying relationship

A relationship in which the primary key of the related entity does not contain a primary key component of the parent entity.

optional attribute

In ER modeling, an attribute that does not require a value; therefore, it can be left empty.

optional participation

In ER modeling, a condition in which one entity occurrence does not require a corresponding entity occurrence in a particular relationship.

participants

An ER term for entities that participate in a relationship. For example, in the relationship "PROFESSOR teaches CLASS," the teaches relationship is based on the participants PROFESSOR and CLASS.

recursive relationship

A relationship found within a single entity type. For example, an EMPLOYEE is married to an EMPLOYEE or a PART is a component of another PART.

relational schema

The organization of a relational database as described by the database administrator.