MS 372 DB Terms

database

organized collection of logically related data

data

stored representations of meaningful objects and events

structured data

numbers, text, dates

unstructured data

images, video, documents

information

data processed to increase knowledge in the person using the data

metadata

data that describes the properties and context of user data

program-data dependence

All programs maintain metadata for each file they use

duplication of data

Different systems/programs have separate copies of the same data

limited data sharing

No centralized control of data

lengthy development times

Programmers must design their own file formats

database management system (DBMS)

A software system that is used to create, maintain, and provide controlled access to user databases.

excessive program maintenance

80% of information systems budget

data models

Graphical system capturing nature and relationship of data

enterprise data model

high-level entities and relationships for the organization

project data model

more detailed view, matching data structure in database or data warehouse

entities

Noun form describing a person, place, object, event, or conceptComposed of attributes

relationships

between entities, usually one to many or many to many

relational databases

Database technology involving tables (relations) representing entities and primary/foreign keys representing relationships

CASE tools

Computer Aided Software Engineering

repository

centralized storehouse of metadata

application programs

software using the data

user interface

text and graphical displays to users

data/database administrators

personnel responsible for maintaining the database

system developers

personnel responsible for designing databases and software

end users

people who use the applications and databases

System Development Life Cycle (SDLC)

approach to database and IS development that is detailed, well-planned, time-consuming but comprehensive, and for a long development cycle

Prototyping

approach to database and IS development that has rapid application development (RAD), defines database during development of initial prototype, and has repeat implementation and maintenance activities

Systems development life cycle stages

planning, analysis, logical design, physical design, implementation, maintenance

external schema

database schema that the user views, is a subset of conceptual schema, and can be determined from business-function/data entity matrices; different people have different views of the database

conceptual schema

E-R models

internal schema

logical structures and physical structures; underlying design and implementation

range of database applications

Personal databases
Two-tier and N-tier Client/Server databases
Enterprise applications- Enterprise resource planning (ERP) systems- Data warehousing implementations

Enterprise Resource Planning (ERP)

Integrate all enterprise functions (manufacturing, finance, sales, marketing, inventory, accounting, human resources)

data warehouse

Integrated decision support system derived from various operational databases

Entity-Relationship model (E-R)

a tool for constructing data models; four versions

Original E-R model

created by Peter Chen in 1976

Extended E-R model

extensions to the Chen model; most widely used model

Information Engineering (IE)

\[James Martin 1990]—Uses "crow's feet" to show the many sides of a relationship, and it is sometimes called the crow's foot model.

IDEF1X

a national standard developed by the National Institute of Standards and Technology

Unified Modeling Language (UML)

A language based on object-oriented concepts that provides tools such as diagrams and symbols to graphically model a system.

attributes

description of the entity's characteristics

entity class

something in general (Order)

entity instance

A single occurrence of an entity type (Order #2345)

composite attribute

attribute consisting of the group of attributes

Multi-valued attribute

attribute with more than one possible value

identifiers

One or more attributes that uniquely identify each entity instance.

unique identifier

the value identifies one and only one entity instance

non-unique identifier

the value identifies a set of instances

composite identifiers

identifiers that consist of two or more attributes

degree of relationship

the number of entity unary relationship, binary relationship, and ternary relationship

Unary (recursive) relationship

a relationship between the instances of one entity type

maximum cardinality

Indicates the maximum number of entities that can be involved in a relationship

minimum cardinality

indicate that there may or may not be an entity in a relationship

weak entities

An entity that depends on another entity for its meaning

associative entity

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

business rules

statements that define or constrain some aspect of the business

data modeling process steps

plan project, determine requirements, specify entities, specify relationships, determine identifiers, specify attributes, specify domains, validate model

subtype

A subgrouping of the entities in an entity type that has attributes distinct from those in other subgroupings

supertype

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

Attribute Inheritance

Subtype entities inherit values of all attributes of the supertypeAn instance of a subtype is also an instance of the supertype

completeness constraint

Whether an instance of a supertype must also be a member of at least one subtype

Total specialization rule

A rule that specifies that each entity instance of a supertype must be a member of some subtype in the relationship.

Partial specialization rule

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

Disjointness Constraint

Whether an instance of a supertype may simultaneously be a member of two (or more) subtypes

Disjoint Rule

An instance of the supertype can be only ONE of the subtypes

overlap rule

An instance of the supertype could be more than one of the subtypes

subtype discriminator

An attribute of a supertype whose values determine the target subtype or subtypes.

disjoint

a simple attribute with alternative values to indicate the possible subtypes

overlap

a composite attribute whose subparts pertain to different subtypes. Each subpart contains a Boolean value to indicate whether or not the instance belongs to the associated subtype

relation

two-dimensional table that has specific characteristicsrows contain data about an entitycolumns contain data about attributes of the entitycells of the table hold a single valueall entries in a column are of the same kindeach column has a unique nameno two rows are identical

file, table

relation terminology in a relation

record, row

tuple terminology in a relation

field, column

attribute terminology in a relation

primary key

unique identifiers of the relation in question

foreign key

identifiers that enable a dependent relation (on the many side of a relationship) to refer to its parent relation (on the one side of the relationship)

referential integrity constraint

what is drawn via arrows from dependent to parent table (relations)

composite attribute in relation

in a relation, uses only simple component attributes (address would display as street name, number etc.)

multivalued attribute in relation

in a relation, becomes a separate relation with foreign key taken from the superior entity

Modification Anomaly

occurs when, in order to modify one value, the same modification has to be made multiple times

Deletion Anomaly

facts about two entities are lost with one deletion

insertion anomaly

cannot insert an entity until info about a second entity is known

Functional Dependency

means of expressing that the value of one particular attribute is associated with a specific single value of another attribute

determinant

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

normalization

The process of applying rules to a database design to ensure that information is divided into the appropriate tables. eliminates modification anomalies by breaking a relation into two or more relations

normal forms

The standards and guidelines of database design that can be used to determine if a database is structured correctly.

1NF (First Normal Form)

A relational database table structure that has no repeating fields or groups of fields

2NF (Second Normal Form)

1NF plus no partial dependencies (dependencies in only part of the primary key).

transitive dependencies

The same record does not contain any data fields where data field A determines data field B. (A->B->C instead of A->B and B->C)