WGU C175/D426 DATA MANAGEMENT EXAM REVIEW
Modality - Answers - 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 - Answers - Requires that ALL foreign key values must either be
fully NULL or match some primary key value.
Ways Referential Integrity can be violated - Answers - 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 - Answers - 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 - Answers - Reference to data in one relation is
based on values in another relation.
Broad definition of data - Answers - Raw facts captured on printed or digital media.
Data - Answers - Facts that are collected and stored in a database system.
Determining characteristic of unstructured data - Answers - It does not follow a data
model.
Flat files - Answers - They contain no internal hierarchical organization.
Data retrieval before database management systems - Answers - Sequentially from
simple files.
Primary Key - Answers - An attribute or group of attributes that uniquely identify a tuple
in a relation.
Foreign Key matching - Answers - 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 - Answers - What uniquely identifies each entity in a collection of entities
but is not the primary key.
,Candidate Key - Answers - A set of columns in a table that can uniquely identify any
record in that table without referring to other data.
Database indexing - Answers - The original data is copied to the index.
Indexes in physical database design - Answers - To retrieve data DIRECTLY using a
pointer.
Index creation on a database column - Answers - To optimize data retrievals.
Functional Dependency - Answers - Each value of a column relates to at MOST one
value of another column.
Rules/Appearance of First Normal Form - Answers - - 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 - Answers - - 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 - Answers - - All non-key columns depend
ONLY on the primary key - Tables are totally free of data redundancy.
Differences between operational and analytical databases - Answers - - Volatility -
Detail - Scope - History.
Volatility - Answers - Database updates in real time. Operational Data is Volatile.
Analytical Data is NOT Volatile.
Detail in databases - Answers - - A database that keeps record of individual
transactions; line items - Operational: Detailed - Analytical: Detailed.
Scope in databases - Answers - - How far a database can reach - Operational:
incompatible - Analytical: Enterprise-Wide/Summary.
History in databases - Answers - - Whether DB is current or tracks all data -
Operational: Current only - Analytical: Tracks trends.
Data warehouse refresh process - Answers - 1. Extraction 2. Cleanse 3. Integrate 4.
Restructure 5. Load.
Extraction in ETL - Answers - Data extracted and put into staging area.
Cleanse in ETL - Answers - Errors are eliminated from data; standard abbreviations
applied.
, Integrate in ETL - Answers - Data is put into a uniform structure; Data converted to
uniform structure.
Restructure in ETL - Answers - Data is structured in a design that is optimal for analysis.
Load in ETL - Answers - Data is loaded to the data warehouse.
Issue focused on 'Load' component of ETL - Answers - Monitor refreshing volume and
frequency.
Step in ETL Process where raw data is aggregated - Answers - Transformation steps.
Data mining activities - Answers - 1. Clustering & Segmentation 2. Classification 3.
Estimation 4. Prediction 5. Affinity Grouping 6. Description.
Clustering & Segmentation - Answers - Taking large entity and dividing into smaller
groups of entities. Useful when unsure of what looking for.
Classification (Data Mining) - Answers - Organizing data into predefined classes.
Estimation (Data Mining) - Answers - Assigning a numeric value to an object.
Prediction (Data Mining) - Answers - Classifying objects according to an expected future
behavior.
Affinity Grouping - Answers - Evaluating relationships between data elements that
demonstrate some kind of affinity between objects.
Entity types - Answers - The uniquely identifiable element about which data can be
categorized in an entity-relationship diagram.
Referential integrity rules by modern relational database management systems -
Answers - Insert, Update, Delete.
DISTINCT clause - Answers - Returns only unique or 'distinct' values; Filters Data
Results.
ORDER BY clause - Answers - Modifies presentation of data results.
Heap file - Answers - A file where records can be placed anywhere in the memory.
Hash file - Answers - 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 - Answers - - LEFT JOIN - RIGHT JOIN - INNER JOIN - FULL JOIN.
Modality - Answers - 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 - Answers - Requires that ALL foreign key values must either be
fully NULL or match some primary key value.
Ways Referential Integrity can be violated - Answers - 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 - Answers - 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 - Answers - Reference to data in one relation is
based on values in another relation.
Broad definition of data - Answers - Raw facts captured on printed or digital media.
Data - Answers - Facts that are collected and stored in a database system.
Determining characteristic of unstructured data - Answers - It does not follow a data
model.
Flat files - Answers - They contain no internal hierarchical organization.
Data retrieval before database management systems - Answers - Sequentially from
simple files.
Primary Key - Answers - An attribute or group of attributes that uniquely identify a tuple
in a relation.
Foreign Key matching - Answers - 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 - Answers - What uniquely identifies each entity in a collection of entities
but is not the primary key.
,Candidate Key - Answers - A set of columns in a table that can uniquely identify any
record in that table without referring to other data.
Database indexing - Answers - The original data is copied to the index.
Indexes in physical database design - Answers - To retrieve data DIRECTLY using a
pointer.
Index creation on a database column - Answers - To optimize data retrievals.
Functional Dependency - Answers - Each value of a column relates to at MOST one
value of another column.
Rules/Appearance of First Normal Form - Answers - - 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 - Answers - - 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 - Answers - - All non-key columns depend
ONLY on the primary key - Tables are totally free of data redundancy.
Differences between operational and analytical databases - Answers - - Volatility -
Detail - Scope - History.
Volatility - Answers - Database updates in real time. Operational Data is Volatile.
Analytical Data is NOT Volatile.
Detail in databases - Answers - - A database that keeps record of individual
transactions; line items - Operational: Detailed - Analytical: Detailed.
Scope in databases - Answers - - How far a database can reach - Operational:
incompatible - Analytical: Enterprise-Wide/Summary.
History in databases - Answers - - Whether DB is current or tracks all data -
Operational: Current only - Analytical: Tracks trends.
Data warehouse refresh process - Answers - 1. Extraction 2. Cleanse 3. Integrate 4.
Restructure 5. Load.
Extraction in ETL - Answers - Data extracted and put into staging area.
Cleanse in ETL - Answers - Errors are eliminated from data; standard abbreviations
applied.
, Integrate in ETL - Answers - Data is put into a uniform structure; Data converted to
uniform structure.
Restructure in ETL - Answers - Data is structured in a design that is optimal for analysis.
Load in ETL - Answers - Data is loaded to the data warehouse.
Issue focused on 'Load' component of ETL - Answers - Monitor refreshing volume and
frequency.
Step in ETL Process where raw data is aggregated - Answers - Transformation steps.
Data mining activities - Answers - 1. Clustering & Segmentation 2. Classification 3.
Estimation 4. Prediction 5. Affinity Grouping 6. Description.
Clustering & Segmentation - Answers - Taking large entity and dividing into smaller
groups of entities. Useful when unsure of what looking for.
Classification (Data Mining) - Answers - Organizing data into predefined classes.
Estimation (Data Mining) - Answers - Assigning a numeric value to an object.
Prediction (Data Mining) - Answers - Classifying objects according to an expected future
behavior.
Affinity Grouping - Answers - Evaluating relationships between data elements that
demonstrate some kind of affinity between objects.
Entity types - Answers - The uniquely identifiable element about which data can be
categorized in an entity-relationship diagram.
Referential integrity rules by modern relational database management systems -
Answers - Insert, Update, Delete.
DISTINCT clause - Answers - Returns only unique or 'distinct' values; Filters Data
Results.
ORDER BY clause - Answers - Modifies presentation of data results.
Heap file - Answers - A file where records can be placed anywhere in the memory.
Hash file - Answers - 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 - Answers - - LEFT JOIN - RIGHT JOIN - INNER JOIN - FULL JOIN.
