Teorey J., Lightstone S., Nadeau T. Database Modeling and Design: Logical Design

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disjointness constraint (d)—symbol in an ER diagram to designate that

the lower-level entities in a generalization relationship have

nonoverlapping (disjoint) occurrences. If the occurrences overlap,

then use the designation (o) instead of (d) in the ER diagram.

entity—a data object that represents a person, place, thing, or event of

informational interest; corresponds to a record in a file when stored.

For example, you could define Employee, Customer, Project, Team,

and Department as entities.

entity cluster—the result of a grouping operation on a collection of

entities and relationships in an ER model to form a higher-level

abstraction that can be used to more easily keep track of the major

components of a large-scale global schema.

entity instance (or occurrence)—a particular occurrence of an entity.

For example, an instance of the entity Actor would be Johnny Depp.

entity–relationship (ER) model—a conceptual data model involving

entities, relationships among entities, and attributes of those entities.

entity–relationship (ER) diagram—a diagram (or graph) of entities and

their relationships, and possibly the attributes of those entities.

exclusion constraint—a symbol (þ) between two relationships in the

ER model that have a common entity that implies that either one

relationship must hold at a given point in time, or the other must

hold, but not both.

existence dependency —there exists a dependency between two entities

such that one is dependent for its existence on the other and cannot

exist alone. For example, an Employee Work-history entity cannot

exist without the corresponding Employee entity. Also refers to the

connectivity between two entities as being mandatory or optional.

fact table—the dominating table in a data warehouse and its star

schema, containing dimension attributes and data measures at the

individual data level.

file—a collection of records of the same type. For example, an employee

file is a collection of employee records.

first normal form (1NF)—a table is in first normal form if and only if

there are no repeating columns of data taken from the same domain

and having the same meaning.

foreign key—any attribute in an SQL table (key or nonkey) that is taken

from the same domain of values as the primary key in another SQL

table and can be used to join the two tables (without loss of data

integrity) as part of an SQL query.

functional dependency (FD)—the property of one or more attributes

(data items) that uniquely determines the value of one or more other

attributes (data items). Given a table R, a set of attributes B is

functionally dependent on another set of attributes A if, at each

instant of time, each A value is associated with only one B value.

generalization—a special type of abstraction relationship that specifies

that several types of entities with certain common attributes can be

generalized (or abstractly defined) with a higher-level entity type, a

supertype entity; an “is-a” relationship. For example, Employee is a

Glossary 297

generalization of Engineer, Manager, and Administrative-assistant

based on the common attribute job-title. A tool often used to make

view integration possible.

global schema—a conceptual data model that shows all the data and

their relationships in the context of an entire database.

key—a generic term for a set of one or more attributes (data items) that,

taken collectively, allows one to identify uniquely an entity or a

record in an SQL table; a superkey.

logical design—the steps in the database life cycle involved with the

design of the conceptual data model (schema), schema integration,

transformation to SQL tables, and table normalization; the design of

a database in terms of how the data is related, but without regard to

how it will be stored.

lossless decomposition—a decomposition of an SQL table into two or

more smaller tables is lossless if and only if the cycle of table

decomposition (normalization) and the recomposition through

joining the tables back through common attributes can be done

without loss of data integrity.

mandatory existence—a connectivity between two entities that has a

lower bound of one. For example, for the “works-in” relationship

between an Employee and a Department, every Department has at

least one Employee at any given time. Note: If this is not true, then

the existence is optional.

multiplicity—in UML, the multiplicity of a class is an integer that

indicates how many instances of that class are allowed to exist.

normalization—the process of breaking up a table into smaller tables to

eliminate problems with unwanted loss of data (the egregious side

effects of losing data integrity) from the deletion of records, and

inefficiencies associated with multiple data updates.

object-relational database—a relational database with object-oriented

concepts added. While not fully object oriented, object-relational

database systems still successfully compete with object-oriented

database systems.

online analytical processing (OLAP)—a query service that overlays a

data warehouse by creating and maintaining a set of summary views

(automatic summary tables, or ASTs) to allow for quick access to

summary data.

optional existence—a connectivity between two entities that has a

lower bound of zero. For example, for the “occupies” relationship

between an Employee and an Office, there may exist some Offices

that are not currently occupied.

package—in UML, a package is a graphical mechanism used to

organize classes into groups for better readability.

physical design—the step in the database life cycle involved with the

physical structure of the data—that is, how it will be stored,

retrieved, and updated efficiently. In particular, it is concerned with

issues of table indexing and data clustering on secondary storage

devices (disks).

298 Glossary

primary key—a key that is selected from among the candidate keys for

an SQL table to be used to create an index for that table.

qualified association—in UML, an association between classes may

have constraints specified in the class diagram.

record—a group of data items treated as a unit by an application; a row

in a database table.

reflexive association—in UML, a reflexive association relates a class to

itself.

referential integrity—a constraint in an SQL database that requires that

for every foreign key instance that exists in a table, the row (and thus

the primary key instance) of the parent table associated with that

foreign key instance must also exist in the database.

relation—a table in a relational database.

relationship—real-world association among one or more entities. For

example, “purchased” could be a relationship between Customer

and Product.

requirements specification—a formal document that defines the

requirements for a database in terms of the data needed, the major

users and their applications, the physical platform and software

system, and any special constraints on performance, security, and

data integrity.

row—a group of data items treated as a unit by an application; a record;

a tuple in relational database terminology.

schema—a conceptual data model that shows all the relationships

among the data elements under consideration in a given context; the

collection of table definitions in a relational database.

second normal form (2NF)—a table is in second normal form if and only

if each nonkey attribute (data item) is fully dependent on the primary

key—that is, either the left side of every functional dependency (FD)

is a primary key or can be derived from a primary key.

star schema—the basic form of data organization for a data warehouse,

consisting of a single large fact table and many smaller dimension

tables.

subtype entity—the higher-level abstract entity in a generalization

relationship.

superkey—a set of one or more attributes (data items) that, taken

collectively, allows one to identify uniquely an entity or a record in a

relational table.

supertype entity—the lower-level entity in a generalization relationship.

table—in a relational database, the collection of rows (or records) of a

single type (similar to a file).

ternary relationship—a relationship that can only be defined among

occurrences of three entities.

third normal form (3NF)—a table is in third normal form if and only if

for every functional dependency X -> A, where X and A are either

simple or composite attributes (data items), either X must be a

superkey or A must be a member attribute of a candidate key in that

table.

Glossary 299

tuple—a row in a relational table; a record.

UML—Unified Modeling Language; a popular form of diagramming

tools used to define data models and processing steps in a software

application.

view integration—a step in the logical design part of the database life

cycle that collects individual conceptual data models (views) into a

single unified global schema. Techniques such as generalization are

used to consolidate the individual data models.

XML—the eXtensible Markup Language used to represent data and

transfer it between systems, particularly for Web technologies.

300 Glossary

INDEX

Note: Page numbers followed by f indicate figures and t indicate tables.

Abstraction, 142–143

Active data warehousing, 254

Activity diagrams

notation description, 48–49

for workflow, 50–52

Aggregation, 27–28

transformation, 98

AllFusion ERwin Data Modeler,

235, 241f, 246f

Anti-pattern, 249, 250–251

Apache web ser ver, 180

Armstrong axioms, 124–128

Association, 39–42

Attributes

attachment, 60

in entityrelationship model,

extraneous, 126–127

of relationships, 21–22

types of, 196–197

value, 18

Binary association, 41

Binary large objects (BLOBs),

156

Binary recursive relationship,

Binary relationship, 87–92

Boyce-Codd normal form

(BCNF), 117–118

Business intelligence

data mining, 222–229

data warehousing, 190–209

definition, 189–190

OLAP, 209–222

Business process

estimating, 201–203

job costing, 207

productivity tracking, 206–207

scheduling, 203–205

Business system life cycle, 234f

Candidate key, 112

Cardenas’ formula, 214

Cardinality, 20

CASE tools

AllFusion ERwin Data

Modeler, 235, 241 f, 246f

application life cycle tooling

integration, 249

basics, 238–239

collaborative support,

246–247

database design process,

235f

database generation, 240–245

database support, 245

data warehouse modeling,

252–255

design compliance checking,

249–251

distributed development,

247–248

ER model, 243t

introduction, 234–237

key capabilities, 237–238

PowerDesigner, 247f, 250f,

253f

Rational Data Architect, 240f

reporting capabilities,

251–252

software tools, 236, 237

XML, 256–257

Character large objects (CLOBs),

157–158

Chen notation, 14f

Class, 141

Class diagram

database design, 39–44

from music industry, 44–47

notation, 37–39

Clustering

entity clusters, 80

ER diagram, 82f

functional grouping, 80

higher-level entity clusters, 81

validate cluster diagram, 81