CS303 Midterm Database I, redux Spring 2022 (Sparks PCC)
The existence-independent table must be created and loaded first because...
A key cannot reference a table that does not yet exist.
composite identifier
A key composed for one or more attributes
existence-independent
A property of an entity that can exist apart from one or more related entities. Such a table must be created first when referencing an existence-dependent table.
existence-dependent
A property of an entity whose existence depends on one or more other entities
A relationship name is always a(n) ______ that describes the relationship?
Active/passive verb
multivalued attribute
An attribute that can have many values for a single entity occurrence
single-valued attribute
An attribute that can have only one value.
derived attribute
An attribute that does not physically exist within the entity and is derived via an algorithm
optional attribute
An attribute that may not have a value for every entity (or relationship) instance with which it is associated.
required attribute
An attribute that must have a value for every entity (or relationship) instance with which it is associated.
An _____ is characteristic of an entity. Difficulty: Easy
Attribute
simple attribute
Attribute that cannot be subdivided
What is the disadvantage of storing derived attributes?
Constant maintenance
What are the three main components of a database?
Entity Attribute Relationship
What are the three disadvantages of not storing derived attributes?
Extra CPU cycles Increases time to access data Code becomes too complex
A subtype contains attributes that are common to all of its supertypes Difficulty: Moderate
False
Composite attributes make it easier to facilitate detailed queries. Difficulty: Easy
False
Disjoint subtypes are subtypes that contain nonunique subsets of the supertype entity set Difficulty: Easy
False
Entity subtypes do not inherit the relationships in which the supertype entity participates Difficulty: Easy
False
In Chen notation, there is no way to represent cardinality Difficulty: Easy
False
In implementation terms, an entity is existence-dependent if it has a mandatory primary key. Difficulty: Easy
False
Overlapping subtypes are subtypes that contain a unique subset of the supertype entity set Difficulty: Easy
False
The Crow's Foot notation easily identifies multivalued attributes. Difficulty: Easy
False
The Crow's Foot notation is less implementation-oriented than the Chen notation. Difficulty: Moderate
False
The entity relationship model (ERM) is dependent on the database type. Difficulty: Easy
False
The function of the primary key is to describe an entity Difficulty: Moderate
False
identifier
One or more attributes that uniquely describe each entity instance.
_____ completeness means that not every supertype occurrence is a member of a subtype Difficulty: Easy
Partial
A _____ relationship occurs when a relationship is tied back to the same entity Difficulty: Easy
Recursive
What are the four advantages of storing derived attributes?
Saves CPU processing cycles Saves time Data value is readily available Can keep track of historical data
What are the two advantages of not storing derived attributes?
Saves space Computation always yields the current value
(T/F) A derived attribute is generally not physically stored in a database
T
(T/F) An entity is the same thing as an object Difficulty: Easy
T
What is this an example of? (0,4) (1,1)
The domain or cardinality
relational schema
The organization of a relational database as described by the database administrator.
_____ completeness means that every supertype occurrence must be a member of at least one subtype Difficulty: Easy
Total
A composite identifier is a primary key composed of more than one attribute. Difficulty: Easy
True
A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity. Difficulty: Easy
True
An entity in the entity relationship model corresponds to a table in the relational environment. Difficulty: Easy
True
At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship Difficulty: Easy
True
Connectivities and cardinalities are established by concise statements known as business rules Difficulty: Easy
True
Entity supertypes and subtypes are organized in a specialization hierarchy Difficulty: Easy
True
In a 1:M relationship, to avoid the possibility of referential integrity errors, the data of the "1" side must be loaded first. Difficulty: Moderate
True
In the Chen and Crow's Foot notations, an entity is represented with a rectangle containing the entity's name. Difficulty: Easy
True
In the entity relationship model, a table row corresponds to an entity instance. Difficulty: Easy
True
In the original Chen notation, each attribute is represented by an oval with the attribute name connected to an entity rectangle with a line. Difficulty: Easy
True
One important inheritance characteristic is that all entity subtypes inherit their primary key attribute from their supertype Difficulty: Easy
True
Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype Difficulty: Moderate
True
The completeness constraint can be partial or total Difficulty: Easy
True
The entity supertype contains common characteristics, and the entity subtypes each contain their own unique characteristics Difficulty: Easy
True
Within a specialization hierarchy, a supertype can exist only within the context of a subtype Difficulty: Easy
True
Your mom gay?
Yes
A _____ attribute can be further subdivided to yield additional attributes. a. composite b. simple c. single-valued d. multivalued Difficulty: Easy
a
A _____ relationship exists when an association is maintained within a single entity. a. unary b. ternary c. binary d. weak Difficulty: Easy
a
A(n) _____ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related. a. subtype discriminator b. inheritance discriminator c. specialization hierarchy d. entity supertype Difficulty: Easy
a
An entity cluster is formed by combining multiple interrelated entities into _____. a. a single abstract entity object b. multiple abstract entity objects c. a single entity object d. multiple entity objects Difficulty: Easy
a
An entity is said to be _____-dependent if it can exist in the database only when it is associated with another related entity occurrence. a. existence b. relationship c. business d. data Difficulty: Easy
a
Ideally, an entity identifier is composed of _____ attribute(s). a. one b. two c. three d. six Difficulty: Moderate
a
One important inheritance characteristic is that all entity subtypes inherit their _____ key attribute from their supertype. a. primary b. entity c. foreign d. surrogate Difficulty: Moderate
a
The "_____" characteristic of a primary key states that the primary key must uniquely identify each entity instance, must be able to guarantee unique values, and must not contain nulls. a. unique values b. nonintelligent c. preferably single-attribute d. security-complaint Difficulty: Easy
a
The entity relationship model uses the associative entity to represent a(n) _____ relationship between two or more entities. a. M:N b. 1:M c. N:1 d. M:1 Difficulty: Moderate
a
A _____ attribute is one that cannot be subdivided. a. composite b. simple c. single-valued d. multivalued Difficulty: Moderate
b
A _____ entity has a primary key that is partially or totally derived from the parent entity in the relationship. a. strong b. weak c. business d. child Difficulty: Easy
b
A relationship is an association between _____. a. objects b. entities c. databases d. fields Difficulty: Easy
b
The conceptual model can handle _____ relationships and multivalued attributes. a. 1:1 b. M:N c. 1:M d. 1:N Difficulty: Moderate
b
The first step in building an entity-relationship diagram (ERD) is _____. a. developing the initial ERD b. creating a detailed narrative of the organization's description of operations c. identifying the attributes and primary keys that adequately describe the entities d. identifying the business rules based on the description of operations Difficulty: Moderate
b
To simplify the conceptual design, most higher-order relationships are decomposed into appropriate equivalent _____ relationships whenever possible. a. ternary b. binary c. strong d. weak Difficulty: Moderate
b
A _____ relationship exists when three entities are associated. a. unary b. strong c. ternary d. weak Difficulty: Easy
c
A _____ relationship exists when two entities are associated. a. unary b. strong c. binary d. weak Difficulty: Easy
c
A total completeness constraint is represented by a _____. a. smaller circle inside a bigger circle b. rhombus inside a circle c. double horizontal line under a circle d. single horizontal line above a circle Difficulty: Easy
c
In the context of total completeness, in a(n) _____, every supertype occurrence is a member of at least one subtype. a. unique constraint b. disjoint constraint c. overlapping constraint d. foreign key constraint Difficulty: Moderate
c
Nonoverlapping subtypes are subtypes that contain a(n) _____ subset of the supertype entity set. a. entity b. subtypes c. unique d. nonunique Difficulty: Easy
c
The _____ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities). a. subtype discriminator b. inheritance c. specialization hierarchy d. entity supertype Difficulty: Easy
c
The _____ specifies whether each entity supertype occurrence must also be a member of at least one subtype Difficulty: Easy
completeness constraint
Another name for derived attribute
computed
A _____ is a primary key created by a database designer to simplify the identification of entity instances. a. composite key b. compound key c. natural key d. surrogate key Difficulty: Easy
d
A(n)_____ is a generic entity type that is related to one or more entity subtypes. a. subtype discriminator b. inheritance c. specialization hierarchy d. entity supertype Difficulty: Easy
d
Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed only once in the _____ relationship. a. 0:1 b. 1:1 c. 1:M d. M:N Difficulty: Easy
d
If an employee within an EMPLOYEE entity has a relationship with itself, that relationship is known as a _____ relationship. a. self b. self-referring c. looping d. recursive Difficulty: Easy
d
If an entity can exist apart from all of its related entities, then it is existence-independent, and it is referred to as a(n) _____ entity. a. weak b. alone c. unary d. strong Difficulty: Easy
d
In the context of total completeness, in a(n) _____, every supertype occurrence is a member of only one subtype. a. foreign key constraint b. nonunique constraint c. overlapping constraint d. disjoint constraint Difficulty: Moderate
d
Knowing the minimum and maximum number of _____ occurrences is very helpful at the application software level. a. object b. attribute c. data d. entity Difficulty: Moderate
d
Overlapping subtypes are subtypes that contain _____ subsets of the supertype entity set. a. null b. exclusive c. solitary d. nonunique Difficulty: Easy
d
The "_____" characteristic of a primary key states that the selected primary key must not be composed of any attribute(s) that might be considered a violation. a. unique values b. nonintelligent c. preferably single-attribute d. security-compliant Difficulty: Easy
d
The entity relationship diagram (ERD) represents the _____ database as viewed by the end user. a. condensed b. physical c. logical d. conceptual Difficulty: Easy
d
_____ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity. a. Connectivity b. Relationship c. Dependence d. Cardinality Difficulty: Moderate
d
The _____ of a relationship indicates the number of entities or participants associated with a relationship Difficulty: Moderate
degree
A(n) _____ attribute need not be physically stored within the database. Difficulty: Moderate
derived
A table row is referred to as a
entity instance or entity occurrence
A weak entity must be _____-dependent. Difficulty: Moderate
existence
In organizations that generate large numbers of transactions, _____ processing speeds are often a top priority in database design, which result in minimal access time. Difficulty: Moderate
high
Composite keys are useful as identifiers of weak entities, where the weak entity has a strong _____ relationship with the parent entity. Difficulty: Moderate
identifying
A(n) _____ process is based on repetition of processes and procedures Difficulty: Easy
iterative
Disjoint subtypes are also known as _____ subtypes Difficulty: Easy
nonoverlapping
Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed _____ in the M:N relationship Difficulty: Moderate
only once
Subtypes that contain nonunique subsets of the supertype entity set are known as _____ subtypes Difficulty: Easy
overlapping
The concept of relationship strength is based on how the _____ of a related entity is defined. Difficulty: Easy
primary key
A weak entity in a strong identifying relationship with a parent entity is normally used to represent a(n) _____ that is represented in the data model as two separate entities Difficulty: Easy
real-world object
A(n) _____ relationship is also known as an identifying relationship Difficulty: Moderate
strong
One practical advantage of a(n) _____ key is that because it has no intrinsic meaning, values for it can be generated by the DBMS to ensure that unique values are always provided. Difficulty: Easy
surrogate
