PATTERNS OF DATA MODELING- P51 pptx

multiple inheritance a generalization for which an entity type inherits information frommultiple supertypes.. non-identifying relationship a relationship that does not contribute to the

multiple inheritance a generalization for which an entity type inherits information from

multiple supertypes (Contrast with single inheritance.)

multiplicity the number of occurrences of one entity type that may connect to an occurrence

of a related entity type Multiplicity is a constraint on the size of a collection (Contrast

with cardinality.)

n-ary relationship a relationship involving three or more relationship ends

non-identifying relationship a relationship that does not contribute to the primary key of

an entity type (Contrast with identifying relationship.)

normal form a guideline for relational database design that increases data consistency (See

denormalization.)

null a special value denoting that an attribute value is unknown or not applicable

Object Constraint Language (OCL) a language for defining constraints within the UML You can also use the OCL to navigate data models

Object Management Group (OMG) a standards forum that is the owner of the UML

OMG (acronym) Object Management Group.

ordered relationship a relationship that has an ordering imposed on a many end

path a sequence of traversals of relationships and generalization levels

pattern a model fragment that is profound and recurring A pattern is a proven solution to

a specified problem that has stood the test of time

primary key a candidate key that is preferentially used for cross-table references Normally, an entity type should have a primary key; an entity type can have at most one

primary key (See alternate key, candidate key, and foreign key.)

qualified relationship a relationship in which one or more attributes (called qualifiers)

disambiguate the entities for a “many” relationship end

qualifier an attribute that selects among the entities at a “many” relationship end

referential integrity a database mechanism that ensures that data references really exist and that there are no dangling foreign keys

relational database a database in which the data are perceived as tables

relational DBMS a DBMS that manages tables of data and associated structures that increase the functionality and performance of tables

relationship a physical or conceptual connection among entities

relationship end an end of a relationship A binary relationship has two ends, a ternary has three ends, and so forth

relationship entity type a relationship that is also an entity type Like a relationship, the occurrences of a relationship entity type derive identity from the related entity types

Like an entity type, a relationship entity type can have attributes and participate in relationships

relationship type a description of a group of relationships with similar structure and meaning

reverse engineering the process of examining implementation artifacts and inferring the underlying logical intent

role one end of a relationship

scenario the execution of a state diagram for an entity of the state diagram’s entity type

schema the structure of the data in a database

seed model a model that is specific to a problem domain A seed model provides a starting point for applications from its problem domain

single inheritance a generalization in which an entity type inherits information from only

one supertype (Contrast with multiple inheritance.)

softcoded value a piece of data that is stored in a generic structure that transcends

indi-vidual entity types (Contrast with hardcoded value.)

SQL the standard language for interacting with a relational database

star schema represents data as facts that are bound to dimensions (See data warehouse, dimension, and fact.)

state diagram a diagram that specifies the permissible states for the entities of an entity type and the stimuli that cause changes of state

strong entity type an entity type that can exist on its own The primary key of a strong entity

type does not include any foreign keys Also called an independent entity type (Contrast with weak entity type.)

structured field a field that is composed from constituent pieces with a specified grammar Structured fields are synthetic but when parsed the pieces have meaning Many struc-tured fields are backed by standard protocols

subject area a group of elements (entity types, relationships, and generalizations) with a common theme that is a portion of a larger model

subtype an entity type that adds specific attributes and relationships for a generalization

(Contrast with supertype.)

supertype the entity type that holds common attribute and relationships for a

generaliza-tion (Contrast with subtype.)

surrogate identity the identification of an entity via another entity with which it is closely related

template an abstract model fragment that is useful for a variety of applications and is devoid of application content Templates are driven by deep data structures that often arise in database models

ternary relationship a relationship among three relationship ends that cannot be restated

as binary relationships

traversal the navigation of a database via foreign-key-to-primary-key bindings

tree a set of nodes that connect from child to parent A node can have many child nodes; each node in a tree has one parent node except for the node at the tree’s top There are

no cycles — that means at most one path connects any two nodes

trigger a database command that executes upon the occurrence of a specified event and satisfaction of a condition

tuning (of a database) the definition of ancillary database structures for the purpose of speeding performance These ancillary structures have no effect on the semantics of the database structure and solely are intended for boosting performance Physical clustering and indexes are common tuning techniques

UML (acronym, trademark of the OMG) Unified Modeling Language.

undirected graph a set of nodes and a set of edges Each edge connects two nodes (which may be the same) The nodes of an undirected graph can have any number of edges

Unified Modeling Language (trademark of the OMG) a suite of models that is often used for software development

universal antipattern an antipattern that should be avoided for all applications

user-defined field an anonymous field in a table that is used to store miscellaneous data Vendors often include a few anonymous fields in important application tables

value-based identity the use of some combination of real-world attributes to identify each

record in a table (Contrast with existence-based identity.)

value metadata affiliated data for a value of an entity For example, a value may have a data source, unit of measure, default value, and time of entry

view a table that a relational DBMS dynamically computes from a query that is stored in the database

weak entity type an entity type that can exist only if some other entity type(s) also exist Accordingly, the primary key of a weak entity type incorporates one or more foreign

keys Also called a dependent entity type (Contrast with strong entity type.)

XML (acronym for eXtensible Markup Language) XML provides a language that

combines data with metadata that defines the data’s structure