WGU C175/D426 Data Management Exam Review
GUARANTEED PASS!!
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.
Primary Key - (ANSWER)An attribute or group of attributes that uniquely identify a tuple in a relation.
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,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.
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, Volatility - (ANSWER)Database updates in real time. Operational Data is Volatile. Analytical Data is NOT
Volatile.
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.
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GUARANTEED PASS!!
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.
Primary Key - (ANSWER)An attribute or group of attributes that uniquely identify a tuple in a relation.
Page 1 of 29
,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.
Page 2 of 29
, Volatility - (ANSWER)Database updates in real time. Operational Data is Volatile. Analytical Data is NOT
Volatile.
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.
Page 3 of 29
