INSY 3304 FINAL REVIEW QUESTIONS
AND ANSWERS 100% CORRECT
Limitations of a File System - ANSWER-Data Dependence: A change in any file's data
characteristics requires changes of all data access programs
Structural Dependence: A change in any file's structure requires the modification of all
programs using that file.
Data Redundancy: lack of data integrity leads to deletion, insertion, and modification
anomalies; the same data is stored unnecessarily at different places
Components of a Database System - ANSWER-A collection of programs that manages
the database structure and controls access to the data stored in the database
Composed of:
Hardware
Software
People
Procedures
Data
Database Models (LOT ABOUT THIS) - ANSWER-Conceptual: represents entities and
relationships
Implementation: install the DBMS on the required hardware, optimize the database to
run best on that hardware and software platform, and create the database and load the
data
Database models can also be considered depending on abstraction.
Conceptual (most abstract): represents a global view of the entire database by the
entire organization; integrates all external views into a single global view of the data in
the enterprise aka conceptual schema. H/S independent
Internal: representation of the database as "seen" by the DBMS; requires the designer
to match the conceptual model's characteristics and constraints to those of the selected
implementation model. S dependent; H independent
External: end users' view of the data environment; easy to identify specific data required
to support each business units operations. S independent; H dependent
, Physical (least abstract): operates at the lowest level of abstraction, describing the way
data are saved on storage media such as magnetic, solid state, or optical media. S/H
dependent
Data Modeling - ANSWER-First step in designing a database; creating a specific data
model for a determined problem domain
Partial Dependency - ANSWER-exists when there is a functional dependence in which
the determinant is only part of the primary key (only part of the primary key is needed to
identify the value of a determinant)
EX: If (A, B) - (C, D) through B - C when (A, B) is the primary key, then B - C is a partial
dependency because you only need B to determine C
Transitive dependency - ANSWER-exists when there are functional dependencies
(occur only when a functional dependence exists among nonprime attributes)
EX: If X - Y, Y - Z, and X is the primary key, then X - Z is transitive because X
determines the value of Z through Y
Concept of a "key" - ANSWER-Determination - state in which knowing the value of one
attribute makes it possible to determine the value of another
Relational Database Model - ANSWER-Entity: person, place, thing, or event about
which data will be collected and stored. Represents a particular type of object in the real
world, which makes it "distinguishable"
Attribute: a characteristic of an entity
Table (Relation): matrix composed of intersecting rows or columns
Row: tuple
Column: attribute
Attribute Domain: the set of values and types allowed in an attribute
Cardinality: expresses the minimum and maximum number of entity occurences
associated with one occurrence of the related entity (expressed in format (x,y) in an
ERD
Connectivity: used to describe classification of entity relationships (i.e., one-to-one, one-
to-many, many-to-many)
AND ANSWERS 100% CORRECT
Limitations of a File System - ANSWER-Data Dependence: A change in any file's data
characteristics requires changes of all data access programs
Structural Dependence: A change in any file's structure requires the modification of all
programs using that file.
Data Redundancy: lack of data integrity leads to deletion, insertion, and modification
anomalies; the same data is stored unnecessarily at different places
Components of a Database System - ANSWER-A collection of programs that manages
the database structure and controls access to the data stored in the database
Composed of:
Hardware
Software
People
Procedures
Data
Database Models (LOT ABOUT THIS) - ANSWER-Conceptual: represents entities and
relationships
Implementation: install the DBMS on the required hardware, optimize the database to
run best on that hardware and software platform, and create the database and load the
data
Database models can also be considered depending on abstraction.
Conceptual (most abstract): represents a global view of the entire database by the
entire organization; integrates all external views into a single global view of the data in
the enterprise aka conceptual schema. H/S independent
Internal: representation of the database as "seen" by the DBMS; requires the designer
to match the conceptual model's characteristics and constraints to those of the selected
implementation model. S dependent; H independent
External: end users' view of the data environment; easy to identify specific data required
to support each business units operations. S independent; H dependent
, Physical (least abstract): operates at the lowest level of abstraction, describing the way
data are saved on storage media such as magnetic, solid state, or optical media. S/H
dependent
Data Modeling - ANSWER-First step in designing a database; creating a specific data
model for a determined problem domain
Partial Dependency - ANSWER-exists when there is a functional dependence in which
the determinant is only part of the primary key (only part of the primary key is needed to
identify the value of a determinant)
EX: If (A, B) - (C, D) through B - C when (A, B) is the primary key, then B - C is a partial
dependency because you only need B to determine C
Transitive dependency - ANSWER-exists when there are functional dependencies
(occur only when a functional dependence exists among nonprime attributes)
EX: If X - Y, Y - Z, and X is the primary key, then X - Z is transitive because X
determines the value of Z through Y
Concept of a "key" - ANSWER-Determination - state in which knowing the value of one
attribute makes it possible to determine the value of another
Relational Database Model - ANSWER-Entity: person, place, thing, or event about
which data will be collected and stored. Represents a particular type of object in the real
world, which makes it "distinguishable"
Attribute: a characteristic of an entity
Table (Relation): matrix composed of intersecting rows or columns
Row: tuple
Column: attribute
Attribute Domain: the set of values and types allowed in an attribute
Cardinality: expresses the minimum and maximum number of entity occurences
associated with one occurrence of the related entity (expressed in format (x,y) in an
ERD
Connectivity: used to describe classification of entity relationships (i.e., one-to-one, one-
to-many, many-to-many)
