SDSU - MIS 380 - Data Management Systems - Test 1

Disjointness Constraints

A constraint that addresses whether an instance of a supertype may simultaneously be a member of two (or more) subtypes.

Relational database

A database that represents data as a collection of tables in which all data relationships by common values in related tables. (1:M One to many/M:N Many to many/M:N Orders and Products/1:1 One to one).

Conceptual Schema

A detailed, technology-independent specification of the overall structure of organizational data.

Recursive Foreign Key

A foreign key in a relation that references the primary key values of the same relation.

Supertype

A generic entity type that has a relationship with one or more subtypes.

Universal data models

A generic or template data model that can be reused as a starting point for a data modeling project.

Entity-Relationship diagram

A graphical representation of an entity-relationship model.

Supertype/subtype hierarchy

A hierarchical arrangement of supertypes and subtypes in which end subtype has only one supertype.

User view

A logical description of some portion of the database that is required by a user to perform some task.

Entity-Relationship model

A logical representation of the data for an organization or for a business area, using entities for categories of data and relationships for associations between entities.

Relationship Type

A meaningful association between (or among) entity types.

Enhanced entity-relationship

A model that has resulted from extending the original E-R model with new modeling constructs.

Relation

A named two-dimensional table of data. Each relation (or tables) consists of named columns and an arbitrary number of unnamed rows.

Entities

A person, place an object, an event, or a concept where the user environment about which organization wishes to maintain data. Example: customer, order.

Project

A planned undertaking of a related activities to reach an objective that has a beginning and an end.

Composite Key

A primary key that consists of more than one attribute.

Attribute inheritance

A property by which subtype entities inherit values of all attributes and instances of all relationships and of their supertype.

Attribute

A property or characteristic of an entity or relationship type that is of interest to the organization.

Well Structured Relations

A relation that contains minimal redundancy and allows users to insert, modify, and delete the rows in a table without errors or inconsistencies.

Unary Relationship

A relationship between instances of a single entity type.

Binary Relationship

A relationship between the instances of two entity types.

Constraint

A rule that cannot be violated by the database users.

Partial specialization rule

A rule that specifies that an entity instance of a supertype is allowed not to belong to any subtype.

Disjoint Rule

A rule that specifies that an instance of a supertype may not be simultaneously be a member of two (or more) subtypes.

Overlap Rule

A rule that specifies that an instance of a supertype may simultaneously be a member of two (or more) subtypes.

Total specialization rule

A rule that specifies that each entity instance of a supertype must be a member of some subtype in the relationship. Indicated by a double line. Category is complete in Visio.

Referential integrity constraint

A rule that states either each foreign key value must match a primary key value in another relation or the foreign key value must be null.

Surrogate primary key

A serial number or other system-assigned primary key for a relation.

Ternary Relationship

A simultaneous relationship among the instances of three entity types.

Database Management System (DBMS)

A software system that us used to create, maintain, and provide access to user databases. Allows information to be stored in one place and not in separate files. (Oracle, etc)

Normal form

A state of a relation that requires that certain rules regarding relationships between attributes (or functional dependence).

Business Rule

A statement that defines or constrains some aspect of the business. It is intended to assert business structure or to control or influence the behavior of the business.

Subtype

A subgrouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroups.

Time stamp

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

Completeness constraint

A type of constraint that addresses whether an instance of a supertype must also be a member of at least one subtype.

Null

A value that may be assigned to an attribute when no other value applies or when the applicable value is unknown.

Term

A word or phrase that has a specific meaning for the business. Examples: course, section, rental car, reservation.

Domain Constraints

Allowable values for an attribute.

Agile Software Development

An approach to database and software development that emphasizes "individuals and interactions over processes and tools, working software over comprehensive documentation, customer collaboration over contract negotiation, and response to change over following a plan." Examples: eXtreme programming, Scrum, DSDM Consortium, Feature-driven development.

Fact

An association between two or more terms.

Identifier

An attribute (or combination of attributes) whose value distinguishes instances of an entity type. That is no two instances of an entity type may have the same value.

Subtype Discriminator

An attribute of the supertype whose values determine the target subtypes(s).

Simple (or atomic) attribute

An attribute that cannot be broken down into smaller components that are meaningful to the organization.

Composite Attribute

An attribute that has meaningful parts (attributes). Example: Address.

Optional Attribute

An attribute that may not have a value for every entity (or relationship) instance with which it is associated.

Required Attribute

An attribute that must have a value for every entity (or relationship) instance with which it is associated.

Derived Attribute

An attribute whose values can be calculated from related attribute values.

Strong Entity type (independent entity)

An entity that exists independently of other entity types. Example: Student, Employee, Automobile. Always have a unique characteristic that distinguish them from a different entity. Has own unique identifier and underlined with single line.

Weak Entity Types (dependent entity)

An entity type whose existence depends on some other entity type. Does not have a unique identifier, and entity box and partial identifier have double lines.

Anomaly

An error or inconsistency that may result when a user attempts to update a table that contains redundant data. The three types of anomalies are insertion, deletion, and modification anomalies.

Composite identifier

An identifier that consists of a composite attribute.

Data warehouse

An integrated decision support database whose content is derive from the various operational databases. Includes personal, workgroup, department, and ERP databases.

Prototyping

An iterative process of systems development in which requirements are converted to a working system that is continually revised through close work between analysts and users.

Database

An organized collection of related data.

First Normal Form

Any multivalued attributes have been removed, so there is a single value (possibly null) at the intersection of each row and column of the table.

Fourth normal form

Any multivalued dependencies have been removed.

Second Normal Form

Any partial functional dependencies have been removed (i.e., nonkey identified by the whole primary key).

Fifth normal form

Any remaining anomalies have been removed.

Boyce-Codd normal form

Any remaining anomalies that result from functional dependencies have been removed (because there was more than one possible primary key for the same nonkeys).

Third Normal Form

Any transitive dependencies have been removed (i.e. nonkey attributes are identified by only the primary key).

Foreign Key

Are identifiers that enable a dependent relation (on the many side of the relationship) to refer to its parent relation (on the one side of the relationship). An attribute in a relation that serves as the primary key of another relation in the same database. Dashed underline.

Primary Key

Are unique identifiers of the relation. An attribute or a combination of attributes that uniquely identifies each row in a relation. Underlined

Regular entities

are entities that have an independent existence and generally represent real-world objects, such as persons and products.

Entity integrity rule

e value is unknown. Entity integrity rule: A rule that states no primary key attribute (or component of a primary key attribute) may be null.

Associative entities

formed from many-to-many relationships between other entity types. Associative entities are represented by a rectangle with rounded corners.

Functional dependency

A constraint between two-attributes in which the value of one attribute is determined by the value of another attribute.

Enterprise resource planning (ERP)

A business management system that integrates all functions of the enterprise, such as manufacturing, inventory, marketing, accounting, and human resources.

Repository

A centralized knowledge base of all data definitions, relationships, screen and report formats, and other system components.

Relationship Instance

A association between (or among) entity instances where each relationship instance associates exactly one entity instance from participating entity type.

Data structure

Data are organized in the form of tables, with rows and columns.

Metadata

Data that describe the properties or characteristics of end-user data and the context of those data. Properties include data names, definitions, length of allowable values, ownership, and usage. Example: Class Roster Size. Distinction between data and metadata is metadata can be removed from the data.

Information

Data that have been processed in such a way to increase the knowledge of the person who uses the data.

Data Model

Graphical systems used to capture the nature and relationships among data. Made up of entities, attributes, and relationships.

Personal Databases

Include someone's PC and the idea if for the ability to manage and store small amounts of data.

Structured data

Includes things such as person name, address, phone number. Stored in tabular form (tables, arrays, spreadsheets).

Multivalued

May Take on more than one value for a given entity (or relationship) instance.

Entity Integrity

No primary key attribute may be null. All primary key fields MUST contain data values.

Data manipulation

Powerful operations (typically implemented using the SQL language) are used to manipulate data stored in the relations.

Integrity Constraint

Refers to maintaining valid data values and relationships in the database.

Legacy System

Refers to the older applications in an organization that are based on file processing and/or older database technology.

Referential Integrity

Rules that maintain consistency between the rows of two related tables.

Entity Cluster

Set of one or more entity types and associated relationships grouped into a single abstract entity type.

Data Modeling and Design Tools

Software tools that provide automated support for creating data models.

Physical Schema

Specifications for how data from a logical schema are stored in a computer's secondary memory by a database management system.

Data

Stored representations of objects that have meaning and importance in the user's environment.

Determinant

The attribute on the left side of the arrow in a functional dependency.

Identifying Owner

The entity type on which the weak entity type depends.

Maximum Cardinality

The maximum number of associated with each instance of another entity.

Minimum cardinality

The minimum number of instances of one entity that may be associated with each instance of another entity.

Data integrity

The model includes mechanisms to specify business rules that maintain the integrity of data when they are manipulated.

Degree

The number of entity types that participate in a relationship.

Normalization

The process of decomposing relations with anomalies to produce smaller, well-structured relations.

Generalization

The process of defining a more general entity type from a set of more specialized entity types.

Specialization

The process of defining one or more subtypes of the supertype and forming supertype/subtype relationships.

Identifying Relationship

The relationship between a weak entity type and its owner.

Logical Schema

The representation of a database for a particular data management technology.

Data independence

The separation of data descriptions from the application programs that use the data.

Systems Development life cycle

The traditional mythology used to develop, maintain, and replace information systems.

Queries

Users can issue commands against the database and examine the results or potentially even store them inside a spreadsheet or document.

Cardinality Constraints

rule that specifies the number of instances of one entity that can (or must) be associated with each instance of another entity.