Chapter 2 Vocab Flashcards
ER 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
ER Diagram
a graphical representation of an ER model
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
Term
a word or phrase that has a specific meaning for the business
Fact
an association between two or more terms
Entity
a person, place, object, or concept in the user environment about which the organization wishes to maintain data
Entity Type
a collection of entities that share common properties or characteristics
Entity Instance
A single occurrence of an entity type
Strong Entity Type
an entity that exists independently of other entity types
Weak Entity Type
an entity type whose existence depends on another entity type
Identifying Owner
the entity type on which the weak entity type depends
Identifying Relationship
the relationship between a weak entity type and its owner
Attribute
a property or characteristic of an entity or relationship type that is of interest to the organization
Required Attribute
an attribute that must have a value for every entity (or relationship) instance with which it is associated
Optional Attribute
an attribute that may not have a value for every entity (or relationship) instance with which it is associated
Composite Attribute
an attribute that has meaningful component parts (attributes)
Simple (Atomic) Attribute
an attribute that cannot be broken down into smaller down into smaller components that are meaningful to the organization
Multivalued Attribute
an attribute that may take on more than one value for a given entity or relationship instance
Derived Attribute
an attribute whose values can be calculated from related attribute values
Identifier
an attribute (or combination of attributes) whose value distinguishes instances of an entity type
Composite Identifier
an identifier that consists of a composite attribute
Relationship Type
a meaningful association between (or among) entity types
Relationship Instance
an association between or among entity instances where each relationship instance associates exactly one entity instance from each participating entity type
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
