2-1 Define each of the following terms:
a. entity type
b. entity-relationship model
c. entity instance
d. attribute
e. relationship type
f. strong entity type
g. multivalued attribute
h. associative entity
i. cardinality constraint
j. weak entity
k. binary relationship
l. derived attribute
m. business rule
2-2. Match the following terms and definitions.
composite attribute
associative entity
unary relationship
weak entity
attribute
entity
relationship type
cardinality constraint
degree
Review Questions
Key Terms
a. uniquely identifies entity instances
b. relates instances of a single entity type
c. specifies maximum and minimum number of instances
d. relationship modeled as
an entity type
e. association between entity types
f. collection of similar entities
g. number of participating entity types in relationship
h. property of an entity
i. can be broken into component parts
2-3. Contrast the following terms:
a. stored attribute; derived attribute
b. minimum cardinality; maximum cardinality
c. entity type; relationship type
d. strong entity type; weak entity type
e. degree; cardinality
f. required attribute; optional attribute
g. composite attribute; multivalued attribute
h. ternary relationship; three binary relationships
Sample Solution