WGU C175/D426 DATA MANAGEMENT FOUNDATIONS OA EXAM
ACTUAL EXAM 2 LATEST VERSIONS 300 QUESTIONS AND
CORRECT DETAILED ANSWERS WITH RATIONALES (100%
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CORRECT AND VERIFIED ANSWERS)|ALREADY GRADED A+
VERSION A
What does modality refer to? How does it appear on ER diagram? - ANSWERRefers 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? - ANSWERSequentially 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
Database updates in real time
- Operational Data is Volatile
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
What are the 4 ways that operational and analytical databases differ? - ANSWER-
- Volat ility
- Detail
- Scope
- History
Define: Volatility; How it applies to Operational? Analytical? - ANSWER- -
- Analytical Data is NOT Volatile
Define: Detail; How it applies to operational and analytical DB? - ANSWER- - A
database that keeps record of individual transactions; line items
- Operational: Detailed
- Analytical: Detailed
Define: Scope; How it applies to operational and analytical DB? - ANSWER- -
What term is used to describe: a value of one particular attribute associated with a
specific single value of another attribute? - ANSWER- Functional Dependency
How far a database can reach
- Operational: incompatible
- Analytical: Enterprise-Wide/Summary
Define: History; How it applies to operational and analytical DB? - ANSWER- -
Whether DB is current or tracks all data
- Operational: Current only
- Analytical: Tracks trends
Data warehouses are refreshed periodically with a 5-step process: - ANSWER- 1.
Extraction
2. Cleanse
3. Integrate
4. Restructure
5. Load
What happens during Extraction? (ETL) - ANSWER- Data extracted and put into
staging area
What happens during Cleanse? (ETL) - ANSWER- Errors are eliminated from
data; standard abbreviations applied
What happens during Integrate? (ETL) - ANSWER- Data is put into a uniform
structure; Data converted to uniform structure
What happens during Restructure? (ETL) - ANSWER- Data is structured in a
design that is optimal for analysis
What happens during Load? (ETL) - ANSWER- Data is loaded to the data
warehouse
What is an issue that is focused on the 'Load' component of ETL? - ANSWERMonitor refreshing volume and frequency
During which step in the ETL Process, is raw data aggregated? - ANSWERTransformation steps
What are the 6 different data mining activities? - ANSWER- 1. Clustering &
Segmentation
2. Classification
3. Estimation
4. Prediction
5. Affinity Grouping
6. Description
Define: Clustering & Segmentation - when is it helpful? - ANSWER- - Taking
large entity and dividing into smaller groups of entities
- Useful when unsure of what looking for
Define: Classification (Data Mining) - ANSWER- - Organizing data into
predefined classes
Define: Estimation (Data Mining) - ANSWER- - Assigning a numeric value to an
object
Define: Prediction (Data Mining) - ANSWER- - Classifying objects according to
an expected future behavior
Define: Affinity Grouping - ANSWER- Evaluating relationships between data
elements that demonstrate some kind of affinity between objects
Where does affinity grouping occur in data mining? - ANSWER- Between objects
What is the uniquely identifiable element about which data can be categorized in
an entity-relationship diagram? - ANSWER- Entity types
Which 3 rules for referential integrity are provided by modern relational database
management systems? - ANSWER- Insert
Update
Delete
What does the DISTINCT clause do? - ANSWER- Returns only unique or 'distinct'
values; Filters Data Results
What does the ORDER BY clause do? - ANSWER- Modifies presentation of data
results
Which SQL statement alphabetizes customer names within the same satellite-office
city? - ANSWER- ORDER BY SATCITY, CUSTNAME
What is a heap file? - ANSWER- A file where records can be placed anywhere in
the memory
What is a 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
What are the different types of major Joins? - ANSWER- - LEFT JOI [Show Less]