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
- Foreign key is updated
- Row containing primary key is DELETED
- Row containing foreign key is INSERTED
4 Actions to Correct Referential Integrity Violation: – ANSWER- 1. RESTRICT –
rejects an insert, update, or delete - SET NULL – sets invalid foreign keys to null
- SET DEFAULT – sets invalid foreign keys to a default primary value
- 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
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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? – ANSWERA 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
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What term is used to describe: a value of one particular attribute associated with a
specific single value of another attribute? – ANSWER- Functional Dependency
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- - Volatility
- Detail
- Scope
- History
Define: Volatility; How it applies to Operational? Analytical? – ANSWER- –
Database updates in real time - Operational Data is Volatile
- 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- –
How far a database can reach - Operational: incompatible
- Analytical: Enterprise-Wide/Summary
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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
- Cleanse
- Integrate
- Restructure
- 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
- Classification
- Estimation
- Prediction
- Affinity Grouping
- Description
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