Quiz 3
In the E-R model, a key that consists of more than one attribute is described as __________
composite
In the E-R model, an attribute that can be broken down into smaller attributes is called __________.
composite
In the E-R model, the number of entities that can map to one another under a relationship is called the __________
degree of the relationship
In the E-R model, if the value of an attribute is determined by a calculation on the value of another attribute in a relation, we call the first attribute __________
derived
In an EE-R diagram, the letter d in a specialization circle stands for __________
disjoint
In the EE-R model, if entity instances cannot belong to more than one subclass, we say the subclasses are __________
disjoint
On an E-R diagram using (min,max) notation, if the line from the entity set Employee to the relationship Assign has (1,3) it indicates __________
every employee has some assignment, and at most 3
In the E-R model, all of the following describe entity Y as existence dependent on entity X EXCEPT __________
for X to exist, Y must exist
Of the following types of keys, the one that does not appear in the entity-relational model is __________
foreign key
In a business, if a department can have many workers, but each worker belongs to only one department, the cardinality of the department-to-worker relationship is __________
one-to-many
In a library, the relationship between the borrower entity set and the books entity set normally has cardinality of __________
one-to-many
In an E-R diagram, attributes are represented by __________
ovals
In the EE-R model, if entity instances can belong to more than one subclass in a specialization, the subclasses are __________
overlapping
In a university, students can get at most one parking permit for one car. Not every student has a car. No car is allowed on campus without a parking permit. In the E-R model, the participation constraint for car in the relationship to student is __________
partial
In the EE-R model, if subclass membership can be determined by examining a condition for each subclass, we describe the specialization as __________
predicate-defined
In the E-R model, when an entity set is related to itself, we call the relationship __________
recursive
In the E-R model, connections or interactions between entities are called __________.
relationships
In the EE-R model, the process of identifying subsets of existing entity set is called __________
specialization
Any attribute or set of attributes that uniquely identifies an entity is called a __________
superkey
In the E-R model, which of the following is true about weak entities?
Every weak entity is existent-dependent
In the E-R model, which of the following is NOT always true about a weak entity?
It always has one attribute which serves as a discriminator
The basic objects in the E-R model include all of the following EXCEPT __________
classes
The entity-relationship model was developed by __________
Peter Chen
In the E-R model, if a relationship R is ternary, it means __________
R is a relationship among three entity sets
In an EE-R diagram, a total specialization is indicated by __________
a double line connecting the circle to the superclass
On an E-R diagram using (min,max) notation, if the line from the entity set Employee to the relationship Assign has (0,M) it indicates __________.
an employee may or may not have an assignment, but can have multiple assignments
In the EE-R model, if a specialization uses the same attribute in the defining predicate for a specialization, it is called __________
attribute-defined
In an EE-R diagram, the specialization circle is sometimes called a(n) __________
isa relationship symbol
In a bank, if we assume that savings accounts can be jointly owned by two or more customers and that a customer can have more than one savings accounts, the relationship between the savings accounts entity set and the customer entity set is __________
many-to-many
In the E-R model, if each entity in set S can be associated with two or more entities in set T, but each entity in T can be associated with only one entity in S, then the binary relationship from S to T is called __________.
many-to-one
In the E-R model, if every member of an entity set must participate in a relationship, the participation is described as __________
total
In the EE-R model, completeness constraints tell us whether a specialization is __________
total or partial
On an E-R diagram, the primary key of an entity is indicated by __________
underlining
In the E-R model, if the value of an attribute is null, it often means the __________
value is unknown
In the E-R model, an entity that is existence-dependent on another and does not have a key of its own is called a __________
weak entity