What does modality refer to? How does it appear on ER diagram? - 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.
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. For-
eign 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 in-
sert, update, or delete 2. SET NULL - sets invalid foreign keys to null 3. SET DEFAULT - sets in-
valid foreign keys to a default primary value 4. CASCADE - propagates primary key changes to
foreign keys.
What is the Important aspect of Referential Integrity - ANSWER Reference to data in one
relation is based on values in another relation.
What is Broad definition of data - ANSWER Raw facts captured on printed or digital me-
dia.
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.
1
,What is true about Flat files - ANSWER They contain no internal hierarchical organiza-
tion.
How were 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.
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 rec-
ord 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 pri-
mary key - Each table cell contains one value - A table with no duplicate rows.
2
,Rules/Appearance of Second Normal Form - ANSWER - When all non-key columns de-
pend 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. Analyti-
cal 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: incompati-
ble - 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. Re-
structure 5. Load.
Extraction in ETL - ANSWER Data extracted and put into staging area.
Cleanse in ETL - ANSWER Errors are eliminated from data; standard abbreviations ap-
plied.
3
, Integrate in ETL - ANSWER Data is put into a uniform structure; Data converted to uni-
form 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 fre-
quency.
Step in ETL Process where raw data is aggregated - ANSWER Transformation steps.
Data mining activities - ANSWER 1. Clustering & Segmentation 2. Classification 3. Estima-
tion 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.
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.
4
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. For-
eign 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 in-
sert, update, or delete 2. SET NULL - sets invalid foreign keys to null 3. SET DEFAULT - sets in-
valid foreign keys to a default primary value 4. CASCADE - propagates primary key changes to
foreign keys.
What is the Important aspect of Referential Integrity - ANSWER Reference to data in one
relation is based on values in another relation.
What is Broad definition of data - ANSWER Raw facts captured on printed or digital me-
dia.
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.
1
,What is true about Flat files - ANSWER They contain no internal hierarchical organiza-
tion.
How were 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.
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 rec-
ord 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 pri-
mary key - Each table cell contains one value - A table with no duplicate rows.
2
,Rules/Appearance of Second Normal Form - ANSWER - When all non-key columns de-
pend 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. Analyti-
cal 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: incompati-
ble - 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. Re-
structure 5. Load.
Extraction in ETL - ANSWER Data extracted and put into staging area.
Cleanse in ETL - ANSWER Errors are eliminated from data; standard abbreviations ap-
plied.
3
, Integrate in ETL - ANSWER Data is put into a uniform structure; Data converted to uni-
form 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 fre-
quency.
Step in ETL Process where raw data is aggregated - ANSWER Transformation steps.
Data mining activities - ANSWER 1. Clustering & Segmentation 2. Classification 3. Estima-
tion 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.
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.
4
