Transcript Lecture 11 & 12

Chapter 7
Storing Organizational
Information - Databases
McGraw-Hill/Irwin
© 2008 The McGraw-Hill Companies, All Rights Reserved
Learning Outcomes
7.1 Define the fundamental concepts of the
relational database model
7.2 Evaluate the advantages of the
relational database model
7.3 Compare relational integrity
constraints and business-critical
integrity constraints
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Learning Outcomes
7.4 Describe the benefits of a data driven
Web site
7.5 Describe the two primary methods for
integrating information across multiple
databases
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Relational Database
Fundamentals
• Information is everywhere in an
organization
• Information is stored in databases
– Database – maintains information about
various types of objects (inventory), events
(transactions), people (employees), and
places (warehouses)
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What is the purpose of a database?
• Spreadsheet and database keep track of
things
• Spreadsheets
– Keep lists of single concept
• Databases
– Keep lists that involve multiple themes
7-5
Database Models
• Database models include:
– Hierarchical database model – information is
organized into a tree-like structure (using
parent/child relationships) in such a way that it
cannot have too many relationships
– Network database model – a flexible way of
representing objects and their relationships; each
record may have multiple parents
– Relational database model – stores information
in the form of logically related two-dimensional
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tables
Hierarchical database model
Instrumental
Music
X
A method for
storing data in a
database that
looks like a family
tree with one root
and a number of
branches or
subdivisions.
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Network database model
A database design for storing information by linking all records that
are related with a list of pointers.
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Relational database model
A design used in database
systems in which
relationships are created
between one or more tables
based on the idea that each
pair of tables has a field in
common.
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Relational Databases
In the rest of this course we only focus of
Relational Databases since they are far
more applicable to businesses.
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Entities and Attributes
• Entity – a person, place, thing, transaction, or
event about which information is stored
– The rows in each table contain the entities
• Attributes (fields, columns) – characteristics or
properties of an entity class
– The columns in each table contain the attributes
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Keys and Relationships
• Primary keys and foreign keys identify the
various entity classes (tables) in the
database
– Primary key – a field (or group of fields) that
uniquely identifies a given entity in a table
– Foreign key – a primary key of one table that
appears an attribute in another table and acts
to provide a logical relationship among the
two tables
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Keys and Relationships
• Potential relational database for Coca-Cola
Primary Key
Foreign Key
Primary
Key
Foreign Key
Foreign
Key
Primary
Key
Foreign Key
Primary
Key
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Another example of Relationships among
tables
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Why Relational models
• What is wrong with putting all information
in the previous slide all in ONE table?
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Relational Database Advantages
• Database advantages from a business
perspective include
– Increased flexibility
– Increased scalability and performance
– Reduced information redundancy
– Increased information integrity (quality)
– Increased information security
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Increased Flexibility
• A well-designed database should:
– Handle changes quickly and easily
– Provide users with different views
– Have only one physical view
• Physical view – deals with the physical storage of
information on a storage device such as hard drive
– Have multiple logical views
• Logical view – focuses on how users logically
access information
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Increased Scalability and Performance
• A database must scale to meet increased
demand, while maintaining acceptable
performance levels
– Scalability – refers to how well a system can
adapt to increased demands
– Performance – measures how quickly a
system performs a certain process or
transaction
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Reduced Information Redundancy
• Databases reduce information
redundancy
– Redundancy – the duplication of information
or storing the same information in multiple
places
• Inconsistency is one of the primary
problems with redundant information
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Increase Information Integrity (Quality)
• Information integrity – measures the quality
of information
• Integrity constraint – rules that help ensure
the quality of information
– Relational integrity constraint
– Business-critical integrity constraint
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Increased Information Security
• Information is an organizational asset and must
be protected
• Databases offer several security features
including:
– Password – provides authentication of the user
– Access level – determines who has access to the
different types of information
– Access control – determines types of user access,
such as read-only access
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Databases, and then what ?
• It provides a framework to store large-scale
networked data
– Increased flexibility
– Increased scalability and performance
– Reduced information redundancy
– Increased information integrity (quality)
– Increased information security
• Ok, we got a database, so now how we can get
(Organizational) Information?
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Database Management Systems
• Database management systems (DBMS) –
software through which users and application
programs interact with a database
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DATA-DRIVEN WEB SITES
• Data-driven Web sites – an interactive Web
site kept constantly updated and relevant to
the needs of its customers through the use of
a database
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Data-Driven Web Site Business
Advantages
• Development
Developing DB  Website Interface
• Content Management
• Future Expandability
• Minimizing Human Error
Driven from the Database
Easier, by extending the DB
Driven from the Database
• Cutting Production and Update Costs
• More Efficient
• Improved Stability
Only requires DB updates
Efficient Querying through DB
Utilize the power of DB security
and Scalability
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Data-Driven Business Intelligence
• BI in a data-driven Web site
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Integrating Information
among Multiple Databases
• Integration – allows separate systems to
communicate directly with each other
– Forward integration – takes information
entered into a given system and sends it
automatically to all downstream systems and
processes
– Backward integration – takes information
entered into a given system and sends it
automatically to all upstream systems and
processes
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Integrating Information
among Multiple Databases
• Forward integration
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Integrating Information
among Multiple Databases
• Backward integration
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Integrating Information
among Multiple Databases
• Building a central repository specifically
for integrated information
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