week 4 Flashcards
(35 cards)
_____________
The process of creating a specific data model for a determined problem domain.
___________
A representation, usually graphic, of a complex “real-world” data structure.
Data models are used in the database design phase of the Database Life Cycle.
data modeling
data model
The Importance of Data Models
● ___________
Data models help bridge communication between designers, application programmers, and end users.
● ______________
A well-structured data model can provide a clearer understanding of how different parts of an organization fit
together.
● _______________
Different users (e.g., managers, clerks, programmers) view data from varying perspectives, and a data model
accommodates these diverse views.
● _____________
Like a blueprint for a house, a data model gives an overall, cohesive view of the data, ensuring consistency
across the organization.
● ____________
A well-designed data model avoids inconsistencies in data usage, which can otherwise lead to costly
mistakes.
● __________________
Just as a blueprint is essential to building a house, a data model is crucial for creating an efficient and
accurate database
Facilitates communication
Improves organizational understanding
Provides different perspectives
Offers a holistic view
Prevents conflicts
Guides database development
Data Model Basic Building Blocks
● An _________ is a person, place, thing, or event about which data will be collected and stored. It
represents a particular type of object in the real world, which means an entity is “distinguishable” —
that is, each entity occurrence is unique and distinct.
● An ___________ is a characteristic of an entity
● A _____________ describes an association among entities
● A __________ is a restriction placed on the data. It is important because they help to
ensure data integrity. They are normally expressed in the form of rules:
○ An employees salary must have values that are between 6,000 and 350,000.
○ A student’s GPA must be between 0.00 and 4.00.
○ Each class must have one and only one teacher
entity
attribute
relationship
constraint
Data Models use Three Types of Relationships
● ________________
Associations among two or more entities that are used by data models. One entity instance is associated with many instances of the related entity.
● ____________________
Association among two or more entities in which one occurrence of an entity is associated
with many occurrences of a related entity and one occurrence of the related entity is associated with
many occurrences of the first entity.
● __________________
Associations among two or more entities that are used by data models. In a 1:1 relationship,
one entity instance is associated with only one instance of the related entity
One-to-many (1:M or 1..*) relationship
Many-to-many (M:N or ..) relationship
One-to-one (1:1 or 1..1) relationship
The Evolution of Data Models
➔ Hierarchical
➔ Network
➔ Relational
➔ Entity relationship
➔ Object oriented (00)
_______________
An early database model whose basic concepts and characteristics formed the basis for subsequent
database development.
This model is based on an upside-down tree structure in which each record is called a ___________
The top record is the ____________. Each segment has a 1:M relationship to the segment directly below it.
The hierarchical model depicts a set of one-to-many (1:M) relationships between a parent and its children
segments.
➔ each parent can have many children
➔ each child has only one parent
Hierarchical model
segment.
root segment
Benefits of Hierarchical Model
Efficiency: Allowed ____________ compared to file-based systems.
Clear Relationships: _____________ made it easy to see connections.
Example: Used in banking and telecommunication systems.
Limitations of Hierarchical Model
___________: Data relationships are inflexible; one-to-one or one-to-many relationships only.
_____________: Complex many-to-many relationships not easily represented.
________________: Difficult to search across branches
faster data retrieval
Simple parent-child structure
Rigidity
Difficult to Model Complex Data
Limited Query Flexibility
________ was created to represent complex data relationships more effectively than the
hierarchical model, to improve database performance, and to impose a database standard.
● the user perceives the network database as a collection of records in 1:M
relationships.
● Network model allows a record to have more than one parent
Example: CODASYL DBTG (Conference on Data Systems Languages Database Task Group
Network Model
Benefits of Network Model
_________: Supports complex data relationships that the hierarchical model couldn’t handle.
_____________: Users could efficiently navigate the graph structure to retrieve related records.
__________: Ideal for managing supply chains, telecommunications, and airline reservation systems.
Limitations of Network Model
____________: More complex to design and implement compared to hierarchical models.
_____________: Required expert knowledge to manage and query data.
___________: Changes to the database structure could be cumbersome.
Flexibility
Efficient Data Navigation
Use Cases
Complexity
Steep Learning Curve
Difficult to Modify
Standard database concepts
○ The ___________ is the conceptual organization of the entire database as viewed by the database
administrator.
○ The_____________ defines the portion of the database “seen” by the application programs that actually
produce the desired information from the data within the database.
○ A _______________ (DML) defines the environment in which data can be managed and is
used to work with the data in the database.
○ A ________________ (DDL) enables the database administrator to define the schema
components
schema
subschema
data manipulation language
schema data definition language
➢ developed by Codd of IBM in 1970
➢ is based on mathematical set theory and represents data as independent relations
➢ data stored in tables (relations), with rows (tuples) and columns (attributes)
➢ produced an “automatic transmission” database to replace the “standard transmission” databases
that preceded it
➢ is implemented through a very sophisticated relational database management system (RDBMS)
Key Features:
● Based on mathematical set theory
● Relations allow easy data manipulation and queries
Examples: SQL, Oracle, MySQL__
Relational Model
Benefits of Relational Model
____________: Easier to understand and use compared to hierarchical and network models.
___________: SQL enables complex queries with simple commands.
___________: Tables can easily be joined to form new relationships.
______________: Relational databases like Oracle and MySQL are industry standards.
Limitations of Relational Model
______________: As data grows, relational databases can struggle with performance
and scalability.
_____________: Works best for structured data; less effective for unstructured data like multimedia.
_____________: Modifying the schema can be time-consuming, especially in large databases
Simplicity
Powerful Querying
Flexibility
Widespread Use
Performance Issues with Big Data
Structured Data Only
Schema Changes
________________
❖ performs the same basic functions provided by the hierarchical and network DBMS systems, in
addition to a host of other functions that make the relational data model easier to understand and
implement
❖ most important advantage is its ability to hide the complexities of the relational
model from the user
❖ manages all of the physical details, while the user sees the relational database as a
collection of tables in which data is stored
❖ The software translates a user’s logical requests (queries) into commands that physically locate
and retrieve the requested data
Relational Database Management System (RDBMS)
______________
A logical construct perceived to be a two-dimensional structure composed of intersecting rows (entities)
and columns (attributes) that represents an entity set in the relational model
____________
In the relational model, a table row
_____________
A graphical representation of a relational database’s entities, the attributes within those entities, and the
relationships among the entities
table (relation)
tuple
relational diagram
A relational table stores a collection of related entities.
● Unlike a file, a relational table provides _________________.
● The table is a ____________; the physical storage of data is ________ to
users or designers.
● This __________ led to a significant breakthrough in database technology.
● The rise of the relational data model is due to its powerful and flexible____________
● SQL allows users to define what data to retrieve without specifying how to
retrieve it.
● SQL simplifies data retrieval compared to other database or file systems
complete data and structural
independence
logical structure
irrelevant
abstraction
query language, SQL.
From an end-user perspective, an SQL-based relational database has three parts:
the __________________
_________________
Allows users to interact with data by automatically generating SQL code. Interfaces vary based on
the software vendor but can be customized with application generators.
A ______________ in the database
All data is stored in independent tables that present information in an easy-to-understand format.
Rows in different tables are linked by common attributes.
________
Executes data queries behind the scenes. It processes user requests for creating tables, accessing
data, and performing maintenance without users needing to know how it works, as SQL specifies what
must be done, not how
user interface, tables, and the SQL engine.
End-user interface
collection of tables stored
SQL engine
________________
○ Widely accepted and adapted graphical tool for data modeling
○ Introduced by Chen in 1976
○ Graphical representation of entities and their relationships in a database structure
○ A data model that describes relationships (1:1, 1:M, and M:N) among entities at the conceptual level
with the help of ER diagrams
Entity Relationship (ER) Model (ERM)
The Entity-Relationship (ER) model is based on three main components:
___________ is any object or concept about which data is collected and stored.
In an Entity-Relationship Diagram (ERD), it is represented by a _________ with the entity’s name in capital
letters and singular form.
_____________: Each entity has it that describe particular characteristics. Attributes are detailed in
ERDs to provide information about each entity.
___________ describe associations among datar. They typically describe associations
between two entities and are categorized into one-to-many (1:M), many-to-many (M:N), and one-to-one
(1:1) types.
Entity
rectangle
Attributes
Relationships
___________
A diagram that depicts an entity relationship model’s entities, attributes, and relations.
_______________
A row in a relational table.
___________
A collection of like entities.
________________
The type of relationship between entities.Classifications include 1:1, 1:M, and M:N.
_____________
A method for creating Entity-Relationship Diagrams (ERDs) where entities are represented by rectangles, attributes
by ovals, and relationships by diamonds, with cardinality shown through lines and annotations.
______________
A representation of the entity relationship diagram that uses a three-pronged symbol to represent the “many” sides of
the relationship.
___________
The set of symbols used in the creation of class diagrams
entity relationship diagram (ERD)
entity instance (entity occurrence)
entity set
Connectivity
Chen notation
Crow’s Foot notation
class diagram notation
______________
Increasing complexity in real-world problems required a data model that better represents real-world
entities.
_____________
❏ Encapsulates both data and relationships in a single structure known as an __________.
❏ Basis for Object-Oriented Database Management System (OODBMS).
❏ Is said to be a _______________
Object Oriented Model
Object-Oriented Data Model (OODM):
object
semantic data model
OODM Components
________ Abstractions of real-world entities, representing individual occurrences of an entity.
__________ Properties that describe an object’s characteristics, such as Name or Social Security Number for a PERSON
object.
_________ Collections of similar objects with shared attributes and methods, defining the structure and behavior of objects.
Classes group objects and include methods that define their actions.
__________ An organizational structure resembling an upside-down tree, where each class has a single parent class,
allowing for inheritance of attributes and methods.
__________ The ability for subclasses to inherit attributes and methods from parent classes, facilitating reuse and
extension of existing class definitions.
____________ Used to visually represent the structure and relationships of objects within the system, based on
object-oriented concepts.
Objects:
Attributes:
Classes:
Class Hierarchy:
Inheritance:
UML Class Diagrams:
______________
Data management software used to manage data in an object-oriented database model.
______________
The first of a series of data models that models both data and their relationships in a single
structure known as an object.
__________
A collection of similar objects with shared structure (attributes) and behavior (methods). A class
encapsulates an object’s data representation and a methods implementation.
___________
In the object-oriented data model, a named set of instructions to perform an action. Represents real-world actions
object-oriented database management system (OODBMS)
semantic data model
class
method
Object/Relational and XML
_____________________________
A model that includes the object-oriented model’s best features in an inherently simpler relational database
structural environment.
_____________________
A DBMS based on the extended relational model (ERDM). The ERDM, championed by many relational
database researchers, constitutes the relational model’s response to the OODM. This model includes many of the
object-oriented model’s best features within an inherently simpler relational database structure.
_________________
A metalanguage used to represent and manipulate data elements. Unlike other markup languages,
XML permits the manipulation of a document’s data elements. XML facilitates the exchange of
structured documents such as orders and invoices over the Internet
extended relational data model (ERDM)
object/relational database management system (O/R DBMS)
Extensible Markup Language (XML)
Emerging Data Models: Big Data and NoSQL
_________ refers to a movement to find new and better ways to manage large amounts of web- and
sensor-generated data and derive business insight from it, while simultaneously providing high
performance and scalability at a reasonable cost.
Basic characteristics of Big Data databases*: ______________
Big Data
volume, velocity, and variety, or the 3 Vs
