WGU C175/D426 DATA MANAGEMENT
FOUNDATIONS OA ACTUAL EXAM 2 LATEST
VERSIONS 400 QUESTIONS AND CORRECT
VERIFIED ANSWERS WITH RATIONALES
(100% CORRECT) A+ GRADED ASSURED
What does cardinality refer to? How does it appear on ER diagram? - ANSWER -
Refers to the MAXIMUM number of times an instance in one entity can be
associated with instance of another entity (Maxima)
Appears as a 1 or M on the relationship line, closest to entity
What does modality refer to? How does it appear on ER diagram? - ANSWER -
Refers to the MINIMUM number of times an instance in one entity can be
associated with instance of another entity (minima)
Appears as a 0 or 1 on the relationship line, next to cardinality
Define: Referential Integrity - ANSWER -Requires that ALL foreign key values
must either be fully NULL or match some primary key value
4 Ways Referential Integrity can be violated: - ANSWER -1. Primary key is
updated
2. Foreign key is updated
3. Row containing primary key is DELETED
4. Row containing foreign key is INSERTED
4 Actions to Correct Referential Integrity Violation: - ANSWER -1. RESTRICT -
rejects an insert, update, or delete
2. SET NULL - sets invalid foreign keys to null
3. SET DEFAULT - sets invalid foreign keys to a default primary value
4. CASCADE - propagates primary key changes to foreign keys
What is an important aspect to referential integrity? - ANSWER -reference to data
in one relation is based on values in another relation
What is a broad definition of data? - ANSWER -Raw facts captured on printed or
digital media
, What are data? - ANSWER -Facts that are collected and stored in a database
system
What is a determining characteristic of unstructured data? - ANSWER -It does not
follow a data model
What is true about flat files? - ANSWER -- They contain no internal hierarchical
organization
How were data retrieved before database management systems? - ANSWER -
Sequentially from simple files
What is an attribute or group of attributes that uniquely identify a tuple in a
relation? - ANSWER -Primary Key
What is necessary for a primary key in one relation of a database to match with its
corresponding foreign key in another relation of the same database? - ANSWER -
A domain of values
What uniquely identifies each entity in a collection of entities but is not the
primary key? - ANSWER -Alternate Key
What is the term for a set of columns in a table that can uniquely identify any
record in that table without referring to other data? - ANSWER -Candidate Key
What happens to the original data in database indexing? - ANSWER -It is copied
to the index
Why are indexes created in a physical database design? - ANSWER -To retrieve
data DIRECTLY using a pointer
Why is an index created on a database column? - ANSWER -To optimize data
retrievals
Define: Functional Dependency - ANSWER -Each value of a column relates to at
MOST one value of another column
Dependence of one column on another
What term is used to describe: a value of one particular attribute associated with a
specific single value of another attribute? - ANSWER -Functional Dependency
FOUNDATIONS OA ACTUAL EXAM 2 LATEST
VERSIONS 400 QUESTIONS AND CORRECT
VERIFIED ANSWERS WITH RATIONALES
(100% CORRECT) A+ GRADED ASSURED
What does cardinality refer to? How does it appear on ER diagram? - ANSWER -
Refers to the MAXIMUM number of times an instance in one entity can be
associated with instance of another entity (Maxima)
Appears as a 1 or M on the relationship line, closest to entity
What does modality refer to? How does it appear on ER diagram? - ANSWER -
Refers to the MINIMUM number of times an instance in one entity can be
associated with instance of another entity (minima)
Appears as a 0 or 1 on the relationship line, next to cardinality
Define: Referential Integrity - ANSWER -Requires that ALL foreign key values
must either be fully NULL or match some primary key value
4 Ways Referential Integrity can be violated: - ANSWER -1. Primary key is
updated
2. Foreign key is updated
3. Row containing primary key is DELETED
4. Row containing foreign key is INSERTED
4 Actions to Correct Referential Integrity Violation: - ANSWER -1. RESTRICT -
rejects an insert, update, or delete
2. SET NULL - sets invalid foreign keys to null
3. SET DEFAULT - sets invalid foreign keys to a default primary value
4. CASCADE - propagates primary key changes to foreign keys
What is an important aspect to referential integrity? - ANSWER -reference to data
in one relation is based on values in another relation
What is a broad definition of data? - ANSWER -Raw facts captured on printed or
digital media
, What are data? - ANSWER -Facts that are collected and stored in a database
system
What is a determining characteristic of unstructured data? - ANSWER -It does not
follow a data model
What is true about flat files? - ANSWER -- They contain no internal hierarchical
organization
How were data retrieved before database management systems? - ANSWER -
Sequentially from simple files
What is an attribute or group of attributes that uniquely identify a tuple in a
relation? - ANSWER -Primary Key
What is necessary for a primary key in one relation of a database to match with its
corresponding foreign key in another relation of the same database? - ANSWER -
A domain of values
What uniquely identifies each entity in a collection of entities but is not the
primary key? - ANSWER -Alternate Key
What is the term for a set of columns in a table that can uniquely identify any
record in that table without referring to other data? - ANSWER -Candidate Key
What happens to the original data in database indexing? - ANSWER -It is copied
to the index
Why are indexes created in a physical database design? - ANSWER -To retrieve
data DIRECTLY using a pointer
Why is an index created on a database column? - ANSWER -To optimize data
retrievals
Define: Functional Dependency - ANSWER -Each value of a column relates to at
MOST one value of another column
Dependence of one column on another
What term is used to describe: a value of one particular attribute associated with a
specific single value of another attribute? - ANSWER -Functional Dependency
