WGU C175/D426 Data Management Exam Review –2025-2026
Simplified Study Guide with Step-by-Step Explanations of Core
Database Topics and Sample Questions with Correct
Answers||Latest Version!!!
Modality - 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.
Referential Integrity - Answer-Requires that ALL foreign key values
must either be fully NULL or match some primary key value.
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.
Important aspect of Referential Integrity - Answer-Reference to data
in one relation is based on values in another relation.
Broad definition of data - Answer-Raw facts captured on printed or
digital media.
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.
pg. 1
,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.
pg. 2
,Detail in databases - Answer- - A database that keeps record of
individual transactions; line items - Operational: Detailed -
Analytical: Detailed.
Scope in databases - Answer- - How far a database can reach -
Operational: incompatible - Analytical: Enterprise-Wide/Summary
History in databases - Answer- - Whether DB is current or tracks all
data - Operational: Current only - Analytical: Tracks trends.
Data warehouse refresh process - Answer-1. Extraction 2. Cleanse 3.
Integrate 4. Restructure 5. Load.
Extraction in ETL - Answer-Data extracted and put into staging area.
Cleanse in ETL - Answer-Errors are eliminated from data; standard
abbreviations applied.
Integrate in ETL - Answer-Data is put into a uniform structure; Data
converted to uniform structure.
Restructure in ETL - Answer-Data is structured in a design that is
optimal for analysis.
Load in ETL - Answer-Data is loaded to the data warehouse.
Issue focused on 'Load' component of ETL - Answer-Monitor
refreshing volume and frequency.
Step in ETL Process where raw data is aggregated - Answer-
Transformation steps.
Data mining activities - Answer-1. Clustering & Segmentation 2.
Classification 3. Estimation 4. Prediction 5. Affinity Grouping 6.
Description.
Clustering & Segmentation - Answer-Taking large entity and dividing
into smaller groups of entities. Useful when unsure of what looking
for.
Classification (Data Mining) - Answer-Organizing data into
predefined classes.
pg. 3
, Estimation (Data Mining) - Answer-Assigning a numeric value to an
object.
Prediction (Data Mining) - Answer-Classifying objects according to
an expected future behavior.
Affinity Grouping - Answer-Evaluating relationships between data
elements that demonstrate some kind of affinity between objects.
Entity types - Answer-The uniquely identifiable element about which
data can be categorized in an entity-relationship diagram.
Referential integrity rules by modern relational database management
systems - Answer-Insert, Update, Delete.
DISTINCT clause - Answer-Returns only unique or 'distinct' values;
Filters Data Results.
ORDER BY clause - Answer-Modifies presentation of data results.
Heap file - Answer-A file where records can be placed anywhere in
the memory.
Hash file - Answer-A file that uses Hash function computation on
some fields of the records, and the result of that computation
determines where the record is stored.
Major Joins - Answer-- LEFT JOIN - RIGHT JOIN - INNER JOIN -
FULL JOIN.
Joins - Answer-Joins usually compare the foreign key of one table to
the primary key of another table (but can join any columns) - joining
together data from two tables into one table.
LEFT JOIN - Answer-Selects all the rows from the left table, and only
matching rows from the right table.
RIGHT JOIN - Answer-Selects all the rows from the right table, and
only matching rows from the left table.
pg. 4
Simplified Study Guide with Step-by-Step Explanations of Core
Database Topics and Sample Questions with Correct
Answers||Latest Version!!!
Modality - 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.
Referential Integrity - Answer-Requires that ALL foreign key values
must either be fully NULL or match some primary key value.
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.
Important aspect of Referential Integrity - Answer-Reference to data
in one relation is based on values in another relation.
Broad definition of data - Answer-Raw facts captured on printed or
digital media.
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.
pg. 1
,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.
pg. 2
,Detail in databases - Answer- - A database that keeps record of
individual transactions; line items - Operational: Detailed -
Analytical: Detailed.
Scope in databases - Answer- - How far a database can reach -
Operational: incompatible - Analytical: Enterprise-Wide/Summary
History in databases - Answer- - Whether DB is current or tracks all
data - Operational: Current only - Analytical: Tracks trends.
Data warehouse refresh process - Answer-1. Extraction 2. Cleanse 3.
Integrate 4. Restructure 5. Load.
Extraction in ETL - Answer-Data extracted and put into staging area.
Cleanse in ETL - Answer-Errors are eliminated from data; standard
abbreviations applied.
Integrate in ETL - Answer-Data is put into a uniform structure; Data
converted to uniform structure.
Restructure in ETL - Answer-Data is structured in a design that is
optimal for analysis.
Load in ETL - Answer-Data is loaded to the data warehouse.
Issue focused on 'Load' component of ETL - Answer-Monitor
refreshing volume and frequency.
Step in ETL Process where raw data is aggregated - Answer-
Transformation steps.
Data mining activities - Answer-1. Clustering & Segmentation 2.
Classification 3. Estimation 4. Prediction 5. Affinity Grouping 6.
Description.
Clustering & Segmentation - Answer-Taking large entity and dividing
into smaller groups of entities. Useful when unsure of what looking
for.
Classification (Data Mining) - Answer-Organizing data into
predefined classes.
pg. 3
, Estimation (Data Mining) - Answer-Assigning a numeric value to an
object.
Prediction (Data Mining) - Answer-Classifying objects according to
an expected future behavior.
Affinity Grouping - Answer-Evaluating relationships between data
elements that demonstrate some kind of affinity between objects.
Entity types - Answer-The uniquely identifiable element about which
data can be categorized in an entity-relationship diagram.
Referential integrity rules by modern relational database management
systems - Answer-Insert, Update, Delete.
DISTINCT clause - Answer-Returns only unique or 'distinct' values;
Filters Data Results.
ORDER BY clause - Answer-Modifies presentation of data results.
Heap file - Answer-A file where records can be placed anywhere in
the memory.
Hash file - Answer-A file that uses Hash function computation on
some fields of the records, and the result of that computation
determines where the record is stored.
Major Joins - Answer-- LEFT JOIN - RIGHT JOIN - INNER JOIN -
FULL JOIN.
Joins - Answer-Joins usually compare the foreign key of one table to
the primary key of another table (but can join any columns) - joining
together data from two tables into one table.
LEFT JOIN - Answer-Selects all the rows from the left table, and only
matching rows from the right table.
RIGHT JOIN - Answer-Selects all the rows from the right table, and
only matching rows from the left table.
pg. 4
