ch2 Flashcards
modeling data in the organization
data integrity
ensure accuracy and precision in data
ER model
detailed, logical representation of data. Parts: entities, relationships, and attributes
relationship “grammar” model
read maximum cardinality on diagram
go to other side of line. max is always one closest to the other entity (think many)
what data modeling is all about
documenting rules and policies of organization
business rule
statement that defines of constrains some aspect of the business
rules identified by
ask who what when where why how
term
word that has a specific meaning for the business. example: course
fact
association between two or more terms. documented as simple
entity
a noun that organization wants to keep data for
entity type
collection of entities that share common attributes
entity instance
single occurance of an entity type
strong entity type
independent of other entity types
weak entity type
existance depends on some other entity type. if owner is deleted, weak also gets deleted
attribute
property or characteristic that is of interest
required attribute
must be present in each entity instance. often time symbolized by * or boldface
composite attribute
has composite/separate parts. often parts marked in parentheses
simple (atomic) attributes
does NOT have composite parts
mutivalued attribute
field that will have more than one value for each instance. often marked in brackets
derived attribute
values calculated from other values. like age from date. sometimes signified by ‘/’
identifier
unique attribute like ID for each instance. should not have to change
relationship
any association of an interaction between two or more entity types. represent business rules
relationship type
meaningful association between entity types
relationship instance
meaningful association between entity instances. only one of each entity allowed
relationship attribute
attribute that on on the relationship, not the two associated entities. “step away from one to many relationships”
associative entity
associate the instances of one or more entity types. look for many to many cardinality. MARKED BY CURVED RECTANGLE
degree of relationship
number of entitys that participate in the relationship
unary relationship
relationship between instances of ONE entity type
binary relationship
relationship between instances of two entity types
tertiary relationship
simultaneous relationship amoung instances of three entity types
cardinality constraint
rule that specifies number of instances that can have a relationship with another entity
maximum cardinality
maximum number of instances of B that can be associated with A
mandatory one
min and max are both ONE
HIPAA
healthcare record privacy act
time stamp
time associated with data
