Lecture 7: EER

Question 1

EER Stands for

Answer 1

Enhanced ER

Question 2

what does EER has that is not in ERD ?

Answer 2

subclasses and superclasss, specialization/generalization union types and attribute and relationship inheritance

Question 3

The subclass member is considered ….. but in a …role

Answer 3

same entity but in a distinct role

Question 4

(T or F) an entity cant be a subclass without being a member of a superclass

Answer 4

T

Question 5

(T or F) a member of the superclass can only include one subclass

Answer 5

F, it can include as many subclasses as it wishes

Question 6

(T or F) not every subclass has a superclass

Answer 6

F, every subclass must be a member of a superclass

Question 7

(T or F) not every superclass has subclasses

Answer 7

T

Question 8

An entity that is a member of subclass inherits…

Answer 8

inherits all attributes and all relationship of the superclass

Question 9

Specialization is ….

Answer 9

defining a set of subclasses to a superclass (Meaning just giving a superclass some subclasses )

Question 10

In Specialization the subclasses are based upon ….

Answer 10

some characteristics that they share

Question 11

Attributes or relationship of the subclasses are called….

Answer 11

specific or local attributes

Question 12

Generalization is….

Answer 12

the reverse of specialization

Question 13

Specialization is called a …. process

Answer 13

top-down conceptual refinement process

Question 14

Generalization is … process

Answer 14

bottom up conceptual synthesis process

Question 15

Predicate defined or condition defined are called that because

Answer 15

if we can determine exactly those entities that will becomes members of each subclass by a condition the subclasses are called predicate defined

Question 16

Disjoint Constraint means

Answer 16

means an entity can be a member of one subclass at most

Question 17

Overlapping Constraint means

Answer 17

an entity may be a member of more than one

Question 18

total constraint means

Answer 18

every entity mist be a member of some subclass

Question 19

partial constraint

Answer 19

allows entities to belong to any subclasses

Question 20

Hierarchy is

Answer 20

every subclass has one super class

Question 21

Lattice is

Answer 21

every subclass can have one or more super classes (Multiple inheritance)

Question 22

A subclass with more than one superclass is called

Answer 22

a shared subclass

Question 23

Union types (Categories)

Answer 23

single relation with more than one superclass

Question 24

option 1 in mapping the specialization / generalization

Answer 24

creates a relation for all subclasses with a foreign key of the superclass primary key

Question 25

if the relation is total subclasses specialization

Answer 25

create a relation for each subclass and remove the superclass and add all the attribute of all the superclass in each subclass

Question 26

if the relation is disjoint specialization

Answer 26

make a single relation with all attributes of the subclasses in that one relation along with all attributes of all superclass

Question 27

if the relation is overlapping specialization

Answer 27

create a single relation and all attributes of both super and subclasses with a Boolean type to indicates whether a tuple belongs to the subclass

Question 28

If union types hace different keys

Answer 28

we create a new key attribute a surrogate key and create a relation just for it