WGU D465 DATA APPLICATIONS OA EXAM 4
2026 ACTUAL TEST VERIFIED QUESTIONS AND
ANSWERS COMPREHENSIVE STUDY GUIDE
◉ 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.
◉ 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 of Referential Integrity.
Answer: Reference to data in one relation is based on values in
another relation.
,◉ What is Broad definition of data.
Answer: Raw facts captured on printed or digital media.
◉ What Data.
Answer: Facts that are collected and stored in a database system.
◉ Determining characteristic of unstructured data.
Answer: It does not follow a data model.
◉ Flat files.
Answer: They contain no internal hierarchical organization.
◉ Data retrieval before database management systems.
Answer: Sequentially from simple files.
◉ Primary Key.
Answer: An attribute or group of attributes that uniquely identify a
tuple in a relation.
◉ Foreign Key matching.
,Answer: A domain of values 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.
◉ Alternate Key.
Answer: What uniquely identifies each entity in a collection of
entities but is not the primary key.
◉ Candidate Key.
Answer: A set of columns in a table that can uniquely identify any
record in that table without referring to other data.
◉ Database indexing.
Answer: The original data is copied to the index.
◉ Indexes in physical database design.
Answer: To retrieve data DIRECTLY using a pointer.
◉ Index creation on a database column.
Answer: To optimize data retrievals.
◉ Functional Dependency.
, Answer: Each value of a column relates to at MOST one value of
another column.
◉ Rules/Appearance of First Normal Form.
Answer: - All non-key columns depend on primary key - Each table
cell contains one value - A table with no duplicate rows.
◉ Rules/Appearance of Second Normal Form.
Answer: - When all non-key columns depend on the WHOLE primary
key - Must be in 1NF - Non-key column can not depend on just one
part of a composite key - a single primary key is automatically in
2NF.
◉ Rules/Appearance of Third Normal Form.
Answer: - All non-key columns depend ONLY on the primary key -
Tables are totally free of data redundancy.
◉ Differences between operational and analytical databases.
Answer: - Volatility - Detail - Scope - History.
◉ Volatility.
Answer: Database updates in real time. Operational Data is Volatile.
Analytical Data is NOT Volatile.
2026 ACTUAL TEST VERIFIED QUESTIONS AND
ANSWERS COMPREHENSIVE STUDY GUIDE
◉ 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.
◉ 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 of Referential Integrity.
Answer: Reference to data in one relation is based on values in
another relation.
,◉ What is Broad definition of data.
Answer: Raw facts captured on printed or digital media.
◉ What Data.
Answer: Facts that are collected and stored in a database system.
◉ Determining characteristic of unstructured data.
Answer: It does not follow a data model.
◉ Flat files.
Answer: They contain no internal hierarchical organization.
◉ Data retrieval before database management systems.
Answer: Sequentially from simple files.
◉ Primary Key.
Answer: An attribute or group of attributes that uniquely identify a
tuple in a relation.
◉ Foreign Key matching.
,Answer: A domain of values 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.
◉ Alternate Key.
Answer: What uniquely identifies each entity in a collection of
entities but is not the primary key.
◉ Candidate Key.
Answer: A set of columns in a table that can uniquely identify any
record in that table without referring to other data.
◉ Database indexing.
Answer: The original data is copied to the index.
◉ Indexes in physical database design.
Answer: To retrieve data DIRECTLY using a pointer.
◉ Index creation on a database column.
Answer: To optimize data retrievals.
◉ Functional Dependency.
, Answer: Each value of a column relates to at MOST one value of
another column.
◉ Rules/Appearance of First Normal Form.
Answer: - All non-key columns depend on primary key - Each table
cell contains one value - A table with no duplicate rows.
◉ Rules/Appearance of Second Normal Form.
Answer: - When all non-key columns depend on the WHOLE primary
key - Must be in 1NF - Non-key column can not depend on just one
part of a composite key - a single primary key is automatically in
2NF.
◉ Rules/Appearance of Third Normal Form.
Answer: - All non-key columns depend ONLY on the primary key -
Tables are totally free of data redundancy.
◉ Differences between operational and analytical databases.
Answer: - Volatility - Detail - Scope - History.
◉ Volatility.
Answer: Database updates in real time. Operational Data is Volatile.
Analytical Data is NOT Volatile.
