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Transcript
Principles of Information
Systems
Chapter 5
Organizing Data and Information
Why Learn About Database Systems?
• Database systems
process and organize
large amounts of data
• Examples:
– Marketing manager can
access customer data
– Corporate lawyer can
access past cases and
opinions
Principles of Information Systems, Eighth Edition
3
Introduction
• Database: an organized collection of data
• Database management system (DBMS): group of
programs to manage database
– Manipulates database
– Provides an interface between database and the
user of the database and other application programs
• Database administrator (DBA): skilled IS
professional who directs all activities related to an
organization’s database
Principles of Information Systems, Eighth Edition
4
Data Management
• Without data and the ability to process it, an
organization could not successfully complete most
business activities
• Data consists of raw facts
• To transform data into useful information, it must
first be organized in a meaningful way
Principles of Information Systems, Eighth Edition
5
The Hierarchy of Data
Figure 5.1: The Hierarchy of Data
Principles of Information Systems, Eighth Edition
6
The Hierarchy of Data
• Bit (a binary digit): represents a circuit that is
either on or off
• Byte: typically made up of eight bits
• Character: a byte represents a character; the
basic building block of information
– Can be an uppercase letter, lowercase letter,
numeric digit, or special symbol
• Field: typically a name, number, or combination of
characters that describes an aspect of a business
object or activity
Principles of Information Systems, Eighth Edition
7
The Hierarchy of Data (continued)
•
•
•
•
Record: collection of related data fields
File: collection of related records
Database: collection of integrated and related files
Hierarchy of data
– Bits, characters, fields, records, files, and databases
Principles of Information Systems, Eighth Edition
8
Data Entities, Attributes, and Keys
• Entity: generalized class of people, places, or
things (objects) for which data is collected, stored,
and maintained
• Attribute: characteristic of an entity
• Data item: specific value of an attribute
• Key: field or set of fields in a record that is used to
identify the record
• Primary key: field or set of fields that uniquely
identifies the record
Principles of Information Systems, Eighth Edition
9
Data Entities, Attributes, and Keys
(continued)
Figure 5.2: Keys and Attributes
Principles of Information Systems, Eighth Edition
10
The Database Approach
• Traditional approach to data management:
separate data files are created and stored for each
application program
• Database approach to data management: a pool
of related data is shared by multiple application
programs
– Offers significant advantages over the traditional filebased approach
Principles of Information Systems, Eighth Edition
11
The Database Approach (continued)
Figure 5.3: The Database Approach to Data Management
Principles of Information Systems, Eighth Edition
12
The Database Approach (continued)
Table 5.1: Advantages of the Database Approach
Principles of Information Systems, Eighth Edition
13
The Database Approach (continued)
Table 5.1: Advantages of the Database Approach (continued)
Principles of Information Systems, Eighth Edition
14
The Database Approach (continued)
Table 5.2: Disadvantages of the Database Approach
Principles of Information Systems, Eighth Edition
15
Data Modeling and the Relational
Database Model
• When building a database, an organization must
consider:
– Content: What data should be collected and at what
cost?
– Access: What data should be provided to which
users and when?
– Logical structure: How should data be arranged so
that it makes sense to a given user?
– Physical organization: Where should data be
physically located?
Principles of Information Systems, Eighth Edition
16
Data Modeling
• Building a database requires two types of designs
– Logical design: abstract model of how the data
should be structured and arranged to meet an
organization’s information needs
– Physical design: starts from the logical database
design and fine-tunes it for performance and cost
considerations
Principles of Information Systems, Eighth Edition
17
Data Modeling (continued)
• Data model: diagram of data entities and their
relationships
• Entity-relationship (ER) diagrams: data models
that use basic graphical symbols to show the
organization of and relationships between data
Principles of Information Systems, Eighth Edition
18
Data Modeling (continued)
Figure 5.4: An Entity-Relationship (ER) Diagram for a Customer Order
Database
Principles of Information Systems, Eighth Edition
19
The Relational Database Model
• Relational model: describes data in which all data
elements are placed in two-dimensional tables,
called relations, that are the logical equivalent of
files
– Each row of a table represents a data entity
– Columns of the table represent attributes
– Domain: allowable values for data attributes
Principles of Information Systems, Eighth Edition
20
The Relational Database Model
(continued)
Figure 5.5: A Relational Database Model
Principles of Information Systems, Eighth Edition
21
The Relational Database Model
(continued)
• Selecting: eliminates rows according to certain
criteria
• Projecting: eliminates columns in a table
• Joining: combines two or more tables
• Linking: manipulating two or more tables that
share at least one common data attribute to
provide useful information and reports
Principles of Information Systems, Eighth Edition
22
The Relational Database Model
(continued)
Figure 5.6: A Simplified ER Diagram Showing the Relationship Between
the Manager, Department, and Project Tables
Principles of Information Systems, Eighth Edition
23
The Relational Database Model
(continued)
Figure 5.7: Linking Data Tables to Answer an Inquiry
Principles of Information Systems, Eighth Edition
24
The Relational Database Model
(continued)
• Data cleanup: process of looking for and fixing
inconsistencies to ensure that data is accurate
and complete
– Eliminate redundancies (ความซ้ าซ้อน) and
anomalies (ความผิดสภาพ)
Principles of Information Systems, Eighth Edition
25
The Relational Database Model
(continued)
Table 5.3: Fitness Center Dues
Principles of Information Systems, Eighth Edition
26
The Relational Database Model
(continued)
Table 5.4: Fitness Center Members
Table 5.5: Dues Paid
Principles of Information Systems, Eighth Edition
27
Database Management Systems
(DBMSs)
• Creating and implementing the right database
system ensures that the database will support both
business activities and goals
• DBMS: a group of programs used as an interface
between a database and application programs or a
database and the user
Principles of Information Systems, Eighth Edition
28
Overview of Database Types
• Flat file
– Simple database program whose records have no
relationship to one another
• Single user
– Only one person can use the database at a time
– Examples: Access, FileMaker, and InfoPath
• Multiple user
– Allows dozens or hundreds of people to access the
same database system at the same time
– Examples: Oracle, Sybase, and IBM
Principles of Information Systems, Eighth Edition
29
Providing a User View
• Schema: description of the entire database
– Typically used by large database systems to define
tables and other database features associated with a
person or user
• A DBMS can reference a schema (แผน) to find where
to access the requested data in relation to another
piece of data
Principles of Information Systems, Eighth Edition
30
Creating and Modifying the Database
• Data definition language (DDL): collection of
instructions and commands used to define and
describe data and relationships in a specific
database
– Allows the database’s creator to describe the data
and relationships that are to be contained in the
schema
• Data dictionary: detailed description of all the data
used in the database
Principles of Information Systems, Eighth Edition
31
Creating and Modifying the Database
(continued)
Figure 5.10: Using a Data Definition Language to Define a Schema
Principles of Information Systems, Eighth Edition
32
Creating and Modifying the Database
(continued)
Figure 5.11: A Typical Data Dictionary Entry
Principles of Information Systems, Eighth Edition
33
Storing and Retrieving Data
• When an application program requests data from
the DBMS, the application program follows a
logical access path
• When the DBMS goes to a storage device to
retrieve the requested data, it follows a path to the
physical location (physical access path) where the
data is stored
Principles of Information Systems, Eighth Edition
34
Storing and Retrieving Data
(continued)
Figure 5.12: Logical and Physical Access Paths
Principles of Information Systems, Eighth Edition
35
Manipulating Data and Generating
Reports
• Data manipulation language (DML): commands
that manipulate the data in a database
• Structured Query Language (SQL)
– Adopted by the American National Standards
Institute (ANSI) as the standard query language for
relational databases
• Once a database has been set up and loaded with
data, it can produce reports, documents, and other
outputs
Principles of Information Systems, Eighth Edition
36
Manipulating Data and Generating
Reports (continued)
Table 5.6: Examples of SQL Commands
Principles of Information Systems, Eighth Edition
37
Database Administration
• Role of the database administrator (DBA): plan,
design, create, operate, secure, monitor, and
maintain databases
• DBA works with both users and programmers
• A data administrator is responsible for defining and
implementing consistent principles for a variety of
data issues, including setting data standards and
data definitions; a nontechnical position
Principles of Information Systems, Eighth Edition
38
Popular Database Management
Systems
• Popular DBMSs for end users include Microsoft’s
Access and FileMaker Pro
• Complete database management software market
includes:
– Software for professional programmers
– Databases for midrange, mainframe, and
supercomputers
• Examples of open-source database systems:
PostgreSQL and MySQL
• Many traditional database programs are now
available on open-source operating systems
Principles of Information Systems, Eighth Edition
39
Special-Purpose Database Systems
• Some specialized database packages are used for
specific purposes or in specific industries
– Israeli Holocaust Database (www.yadvashem.org)
– Hazmat database
– Art and Antique Organizer Deluxe
• Special-purpose database by Tableau can be used
to store and process visual images
Principles of Information Systems, Eighth Edition
40
Selecting a Database Management
System
• Important characteristics of databases to consider
–
–
–
–
–
–
Database size
Database cost
Concurrent users
Performance
Integration
Vendor
Principles of Information Systems, Eighth Edition
41
Using Databases with Other Software
• DBMSs can act as front-end or back-end
applications
– Front-end applications interact directly with people or
users
– Back-end applications interact with other programs
or applications
Principles of Information Systems, Eighth Edition
42
Database Applications
• Today’s database applications manipulate the
content of a database to produce useful information
• Common manipulations are searching, filtering,
synthesizing, and assimilating the data contained in
a database using a number of database
applications
Principles of Information Systems, Eighth Edition
43
Linking Databases to the Internet
• Linking databases to the Internet is important for
many organizations and people
• Semantic Web
– Developing a seamless integration of traditional
databases with the Internet
– Allows people to access and manipulate a number of
traditional databases at the same time through the
Internet
Principles of Information Systems, Eighth Edition
44
Data Warehouses, Data Marts, and
Data Mining
• Data warehouse: database that collects business
information from many sources in the enterprise,
covering all aspects of the company’s processes,
products, and customers
• Data mart: subset of a data warehouse
• Data mining: information-analysis tool that
involves the automated discovery of patterns and
relationships in a data warehouse
Principles of Information Systems, Eighth Edition
45
Data Warehouses, Data Marts, and
Data Mining (continued)
Figure 5.17: Elements of a Data Warehouse
Principles of Information Systems, Eighth Edition
46
Data Warehouses, Data Marts, and
Data Mining (continued)
Table 5.8: Common Data-Mining Applications
Principles of Information Systems, Eighth Edition
47
Business Intelligence
• Business intelligence (BI): process of gathering
enough of the right information in a timely manner
and usable form and analyzing it to have a positive
impact on business strategy, tactics, or operations
– Turns data into useful information that is then
distributed throughout an enterprise
Principles of Information Systems, Eighth Edition
48
Business Intelligence (continued)
• Competitive intelligence: aspect of business
intelligence limited to information about competitors
and the ways that knowledge affects strategy,
tactics, and operations
• Counterintelligence: steps an organization takes
to protect information sought by “hostile” (ผูม้ ุ่งร้าย)
intelligence gatherers
Principles of Information Systems, Eighth Edition
49
Distributed Databases
• Distributed database
– Database in which the data may be spread across
several smaller databases connected via
telecommunications devices
– Gives corporations more flexibility in how databases
are organized and used
• Replicated database
– Database that holds a duplicate set of frequently
used data
Principles of Information Systems, Eighth Edition
50
Online Analytical Processing (OLAP)
• Software that allows
users to explore data
from a number of different
perspectives
Principles of Information Systems, Eighth Edition
51
Online Analytical Processing (OLAP)
(continued)
Table 5.9: Comparison of OLAP and Data Mining
Principles of Information Systems, Eighth Edition
52
Object-Oriented and Object-Relational
Database Management Systems
• Object-oriented database:
database that stores both
data and its processing
instructions
– Method: procedure or
action
– Message: request to
execute or run a method
Principles of Information Systems, Eighth Edition
53
Object-Oriented and Object-Relational
Database Management Systems
(continued)
• Object-oriented database management system
(OODBMS): group of programs that manipulate an
object-oriented database and provide a user
interface and connections to other application
programs
• Object-relational database management system
(ORDBMS): DBMS capable of manipulating audio,
video, and graphical data
Principles of Information Systems, Eighth Edition
54
Visual, Audio, and Other Database
Systems
• Databases for storing images
• Databases for storing sound
• Virtual database systems: allow different
databases to work together as a unified database
system
• Other special-purpose database systems
– Spatial data technology: stores and accesses data
according to the locations it describes and permits
spatial queries and analysis
Principles of Information Systems, Eighth Edition
55
Summary
• Database: a collection of integrated and related files
• Hierarchy of data: bits, characters, fields, records,
files, and databases
• Key: a field or set of fields in a record that is used to
identify the record
• Database approach to data management: a pool of
related data is shared by multiple application
programs
• Data model: diagram of entities and relationships
Principles of Information Systems, Eighth Edition
56
Summary (continued)
• Relational model: describes data in which all
elements are placed in two-dimensional tables
called relations
• Database management system (DBMS): group of
programs used as an interface between a database
and application programs or a database and the
user
• Role of the database administrator (DBA): plan,
design, create, operate, secure, monitor, and
maintain databases
Principles of Information Systems, Eighth Edition
57
Summary (continued)
• Data warehouse: database that collects business
information from all aspects of a company’s
processes, products, and customers
• Data mining: information-analysis tool for the
automated discovery of patterns and relationships
in a data warehouse
• Object-oriented database: database that stores
both data and its processing instructions
Principles of Information Systems, Eighth Edition
58
Principles of Information Systems, Eighth Edition
59
Principles and Learning Objectives
• Data management and modeling are key aspects
of organizing data and information
– Define general data management concepts and
terms, highlighting the advantages of the database
approach to data management
– Describe the relational database model and outline
its basic features
Principles of Information Systems, Eighth Edition
60
Principles and Learning Objectives
(continued)
• A well-designed and well-managed database is an
extremely valuable tool in supporting decision
making
– Identify the common functions performed by all
database management systems and identify popular
user database management systems
Principles of Information Systems, Eighth Edition
61
Principles and Learning Objectives
(continued)
• The number and types of database applications will
continue to evolve and yield real business benefits
– Identify and briefly discuss current database
applications
Principles of Information Systems, Eighth Edition
62
Review question #5
Principles of Information Systems, Eighth Edition
63
ส วั ส ดี
Principles of Information Systems, Eighth Edition
64