goood databases3147
TRANSCRIPT
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Introduction
Database: an organized collection of dataDatabase management system (DBMS):
group of programs to manage databaseManipulates databaseProvides an interface between database and the
user of the database and other applicationprograms
Database administrator (DBA): skilled ISprofessional who directs all activities relatedto an organizations database
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The Hierarchy of Data
Bit (a binary digit): a circuit thatis either on or off
Byte: eight bits
Character: basic building blockof information Each byte represents a
character
Can be an uppercase letter,lowercase letter, numeric digit,
or special symbol Field: typically a name, number,
or combination of charactersthat describes an aspect of abusiness object or activity
Record: a collection ofrelated data fields
File: a collection of related
records Database: a collection of
integrated and related files
Hierarchy of data: bits,
characters, fields, records,files, and databases
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The Hierarchy of Data
Figure 3.1: The Hierarchy of Data
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Data Entities, Attributes, and Keys
Entity: a generalized class of people, places, orthings (objects) for which data is collected, stored,and maintained
Attribute: characteristic of an entity
Data item: value of an attribute
Key: field or set of fields in a record that is usedto identify the record
Primary key: field or set of fields that uniquelyidentifies the record
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Data Entities, Attributes, and Keys
Figure 3.2: Keys and Attributes
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The Database Approach
Traditional approach to database management:separate data files are created for each
application
Results in data redundancy (duplication)
Data redundancy conflicts with data integrity
Database approach to database management: pool
of related data is shared by multiple applicationsSignificant advantages over traditional approach
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The Database Approach
Figure 3.3: The Database Approach to Data Management
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The Database Approach
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The Database Approach
Table 3.2: Disadvantages of the Database Approach
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Data Modeling and the RelationalDatabase Model
When building a database, consider:
Content:What data should be collected, at what cost?
Access:What data should be provided to which users andwhen?
Logical structure:How should data be arranged to make
sense to a given user?
Physical organization:Where should data be physically
located?
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Data Modeling
Building a database requires two types ofdesigns
Logical designAbstract model of how data should be structured and
arranged to meet an organizations information needs
Physical design
Fine-tunes the logical database design forperformance and cost considerations
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Data Modeling
Data model: a diagramof data entities andtheir relationships
Entity-relationship(ER) diagrams: datamodels that use basic
graphical symbols toshow the organizationof and relationshipsbetween data
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The Relational Database Model Relational model: all data
elements are placed in two-
dimensional tables
(relations), which are the
logical equivalent of files
In the relational model Each row of a table
represents a data entity
Columns of the table
represent attributes Domain: the allowable values
for data attributes
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Manipulating Data
Figure 3.7: Linking Data Tables to Answer an Inquiry
D t b M t S t
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Database Management Systems(DBMS)
Interface between:Database and application programs
Database and the userCreating and implementing the right database
system ensures that the database will support bothbusiness activities and goals
DBMS: a group of programs used as an interfacebetween a database and application programs or adatabase and the user
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Overview of Database Types
Flat file
Simple database program whose records have norelationship to one another
Single user
Only one person can use the database at a timeExamples: Access, FileMaker, and InfoPath
Multiple user
Allows dozens or hundreds of people to access the samedatabase system at the same time
Examples: Oracle, Sybase, and IBM
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Creating and Modifying the Database
Data definition language (DDL)
Collection of
instructions/commands that
define and describe data and
data relationships in a database
Allows database creator to
describe the data and the data
relationships that are to be
contained in the schema Data dictionary: a detailed
description of all the data used
in the database
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Storing and Retrieving Data When an application requests
data from the DBMS, theapplication follows a logicalaccess path
When the DBMS goes to astorage device to retrieve the
requested data, it follows a pathto the physical location (physicalaccess path) where the data isstored
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Manipulating Data and GeneratingReports
Query-By-Example (QBE):a visual approach to developing
database queries or requests
Data manipulation language (DML): commands that
manipulate the data in a database
Structured Query Language (SQL): ANSI standard query
language for relational databases
Database programs can produce reports, documents, andother outputs
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Database Administration
Database administrator (DBA): directs orperforms all activities to maintain a database
environmentDesigning, implementing, and maintaining thedatabase system and the DBMS
Establishing policies and procedures
Employee training
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Popular Database ManagementSystems
Popular DBMSs for end users: Microsoft Access and
FileMaker Pro
Entire market includes databases by IBM, Oracle, and
Microsoft
Examples of open-source database systems: PostgreSQL
and MySQL
Many traditional database programs are now available onopen-source operating systems
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Selecting a DatabaseManagement System
Important characteristics of databases toconsider
Size of the databaseCost of the system
Number of concurrent users
Performance
Ability to be integrated with other systems
Vendor considerations
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Using Databases with OtherSoftware
Database management systems are oftenused with other software packages or the
InternetA database management system can act as a
front-end application or a back-endapplicationFront-end application: interacts with users
Back-end application: interacts with applications
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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
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Data Warehouses, Data Marts, andData Mining
Data warehouse: collects
business information from many
sources in the enterprise
Data mart: a subset of a datawarehouse
Data mining: an information-
analysis tool for discovering
patterns and relationships in adata warehouse or a data mart
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Data Warehouses, Data Marts, and DataMining
Table 3.5: Common Data-Mining Applications
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Business Intelligence
Business intelligence (BI):gathering the right informationin a timely manner and usableform and analyzing it to have apositive impact on business Turns data into useful
information that is thendistributed throughout anenterprise
Competitive intelligence: aspectof business intelligence limitedto information about competitorsand the ways that knowledgeaffects strategy, tactics, andoperations
Counterintelligence: steps anorganization takes to protectinformation sought by hostileintelligence gatherers
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Distributed Databases
Distributed databaseData may be spread across several smaller databases
connected via telecommunications devices
Corporations get more flexibility in how databases areorganized and used
Replicated databaseHolds a duplicate set of frequently used data
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Online Analytical Processing(OLAP)
Software that allows users to explore datafrom a number of different perspectives
Table 3.6: Comparison of OLAP and Data Mining
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Object-Oriented and Object-RelationalDatabase Management Systems
Object-oriented databaseStores both data and its processing instructions
Method: a procedure or action
Message: a request to execute or run a method
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Visual, Audio, and Other DatabaseSystems
Visual databases for storing images
Audio 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
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Video Clip
ChoicePoint http://www.youtube.com/watch?v=bWB3kEw08Gk
http://www.youtube.com/watch?v=bWB3kEw08Gkhttp://www.youtube.com/watch?v=bWB3kEw08Gk