Transcript Relational Database Model - McGraw Hill Higher Education

CHAPTER 07
Storing Organizational
Information – Databases
McGraw-Hill/Irwin
Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved.
LEARNING OUTCOMES
1. Define the fundamental concepts of the relational
database model.
2. Evaluate the advantages of the relational database
model.
3. Define a database management system and its
relationship to a website.
4. Explain why an organization would want to
integrate its databases.
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STORING ORGANIZATIONAL
INFORMATION
• Database management system—Computer
program used to manage and query a database
• Properties typically considered necessary to
constitute a database:
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Data are managed to ensure integrity and quality
Allows shared access across a community of users
Has a schema
Supports a query language
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RELATIONAL DATABASE
FUNDAMENTALS
• Database—Maintains information about various types
of objects (inventory), events (transactions), people
(employees), and places (warehouses)
• Database models include:
– Hierarchical Database Model—Information is organized into
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
– Relational Database Model—Stores information in the form of
logically related two-dimensional tables
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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
– In Figure 7.1 CUSTOMER includes Dave’s Sub Shop
and Pizza Palace entities
• Attributes—Characteristics or properties
of an entity class
– The columns in each table contain the
attributes
– In Figure 7.1 attributes for CUSTOMER include
Customer ID, Customer Name, Contact Name
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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 as an attribute in another
table and acts to provide a logical
relationship among the
two tables
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RELATIONAL DATABASE ADVANTAGES
• Database advantages from a business
perspective include:
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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:
1. Handle changes quickly and easily.
2. Provide users with different views.
3. Have only one physical view.
• Physical View—Deals with the physical storage
of information on a storage device.
4. 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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INCREASED INFORMATION INTEGRITY
(QUALITY)
• Information Integrity—Measures the quality of
information
• Integrity Constraint—Rules that help ensure
the quality of information
– Relational Integrity Constraints—Rules that
enforce basic and fundamental information-based
constraints
– Business-Critical Integrity Constraints—Enforce
business rules vital to an organization’s
success and often require more insight
and knowledge than relational integrity
constraints
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INCREASED INFORMATION SECURITY
• 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
• Database Management Systems (DBMS)—
Software through which users and application
programs interact with a database
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DATABASE MANAGEMENT SYSTEMS
• Two primary ways a user can interact with a
DBMS:
– Directly
– Indirectly
• Data-Driven Websites—An interactive website
kept constantly updated and relevant to the
needs of its customers through
the use of a database
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DATA-DRIVEN WEBSITES
• Data-Driven Website Business Advantages:
– Development
– Content management
– Future expandability
– Minimizing human error
– Cutting production and update costs
– More efficient
– Improved stability
• Data-Driven Business Intelligence—Companies can
gain business intelligence by viewing the data access
and analyzed from their website
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INTEGRATING INFORMATON 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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