CIS305_Ch.3

• a statment that defines or constrains some aspect of the business.
• Is intended to assert business structure or to control or influence the behavior of the business

a word or phrase taht has a specific meaning for the business

an association between two or more terms

• relate to business, not technical (HW or SW) characteristics
• be meaningful
• be unique
• be readable
• be composed of words taked from an approved list
• be repeatable
• follow a standard syntax

• Entity-Relationship model.
• a logical representation of the data for an organization or for a business are using entities for categories of data and relationships for associations between entities

• Entity-Relationship Diagram.
• a graphical representation of an entity-relationship model.

a person, place, object, event, or concept in the user environment about which the organization wishes to maintain data

a collection of entities that share common properties or characteristics

a single occurence of an entity type

an entity that exists independently of other entity types

an entity type whose existence depends on some other entity type

the entity type on which the weak entity type depends

the relationship between a weak entity type and its owner

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

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

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

an attribute that has meaningful component part (attributes)

• (or Atomic).
• an attibute that cannot be broken down into smaller components that are meaningful to the organization

an attribute that may take on more than one value for a given entity (or relationship) instance

an attribute whose values can be calculated from related attribute values

an attribute (or combination of attributes) whose value distinguishes instances of an entity type

an identifier that consists of a composite attribute

a meaningful association between (or among) entity types

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

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

the number of entity types that participate in a relationship

a relationship betwen instances of a single entity type

a relationship between the instances of two entity types

a simultaneous relationship among the instances of three entity types

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

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

the maximum number of instances of one entity that may be associated with each instance of another entity

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