Transcript Chapter 7: Database Systems

Chapter 7:
Database Systems
Succeeding with Technology:
Second Edition
Objectives
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Understand basic data management concepts
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Describe database models and characteristics
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Discuss the different types of database
management systems and their design and use by
individuals and organizations
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Objectives (continued)
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Describe how organizations use database systems
to perform routine processing, provide information
and decision support, and how they use data
warehouses, marts, and mining
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Discuss additional database systems, including
distributed systems and Web-based systems
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Describe the role of the database administrator
(DBA) and database policies and security practices
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Basic Data Management Concepts
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Database
 A collection of data organized to meet users’ needs
Database management system (DBMS)
 Software used to access database
Database system
 Comprised of database, DBMS, and application
programs
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Data Management for Individuals
and Organizations
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Individuals use databases to
 Develop monthly budgets
 Store phone numbers and addresses
 Keep track of important dates
 Keep track of valuables for possible insurance claim
 Get information about organizations such as
hospitals
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The Hierarchy of Data
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Field
 Name, number, or combination of characters that
describes some aspect of an object
Record
 Collection of related fields
File
 Collection of related records
Database
 Collection of integrated and related files
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Data Entities, Attributes, and Keys
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Entity
 Generalized class of people, places, or things for
which data is collected, stored, and maintained
Attribute
 Characteristic of an entity
 For example, employee number or last name
Key
 Field in a record used to identify the record
 Primary key
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Uniquely identifies the record
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The Database Approach to Data
Management
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Database approach
 Multiple application programs share a pool of related
data
 Increased flexibility in the use of data
 Requires a database management system (DBMS)
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Organizing Data in a Database
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Questions to be asked when building a database
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What data is to be collected and at what cost
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What data is to be provided to which users when
appropriate
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How is the data to be arranged so that it makes
sense
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Where is the data to be physically located
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Who is responsible for maintaining an accurate
database system
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The Relational Database Model
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Purpose
 To describe data using a standard tabular format
All data elements are placed in two-dimensional
tables called relations
Selecting
 Choosing data based on certain criteria
Joining
 Combining two or more tables
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Data Analysis
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Evaluating data to identify problems with content of
database
Normalization
 Process of correcting data problems or anomalies
 Breaking a table into two or more tables in order to
correct the data problem or anomaly
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Object-Oriented Databases
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Use the same overall approach as objected-oriented
programming
Data and processing instructions are stored in the
database
Offer the ability to reuse and modify existing objects
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Database Characteristics
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Database size or amount
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Volatility of data
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Depends on the number of records or files in the
database
Measure of the changes typically required in a given
period of time
Immediacy
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Measure of how rapidly changes must be made to
data
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Database Management Systems
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Creating and implementing the right database
system involves
 Determining how data is stored and retrieved
 How people will see and use the database
 How the database will be created and maintained
 How reports and documents will be generated
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Overview of Database Types
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Flat file
 Used to store and manipulate a single table or file
Single User
 Only one person can use the database at any time
Multiuser
 Networked computer systems need multiuser
DBMSs
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Overview of Database Types
(continued)
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General-purpose database
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Special-purpose database
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Can be used for a large number of applications
Designed for a limited number of applications
Open-Source database systems
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PostgreSQL, MySQL
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Database Design
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Numeric field
 Contains numbers that can be used in making
calculations
Alphanumeric
 Characters or numbers that will not be manipulated
Date
 Can be sorted or even used in computations
Logical piece of data
 Contains items, such as “yes” or “no”
Computed field
 Determined from other fields
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Using Databases with Other
Software
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Front-end application
 One that directly interacts with people or users
Back-end application
 Interacts with other programs or applications
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Data Accuracy and Integrity
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Data integrity
 Data stored in the database is accurate and up to
date
Garbage in, garbage out (GIGO)
 Inaccurate data input results in inaccurate output
Database management systems
 Must be programmed to detect and eliminate data
inaccuracies
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Creating and Modifying a Database
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Schema
 Outline of the logical and physical structure of the
data and relationships among the data
Data definition language (DDL)
 Collection of instructions and commands
Data dictionary
 Detailed description of all data used in the database
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Creating and Modifying a Database
(continued)
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Typical uses of a data dictionary
 Provide a standard definition of terms and data
elements
 Assist programmers in designing and writing
programs
 Simplify database modification
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Manipulating Data and Generating
Reports
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Data manipulation language (DML)
 Allows users to
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Access, modify, and make queries
Generate reports
Query by example (QBE)
 Makes manipulating databases much easier and
faster
Structured Query Language (SQL)
 Standardized data manipulation language
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Database Backup and Recovery
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Database backup
 A copy of all or part of the database
Database recovery
 Returning database to original, correct condition if it
has crashed or has been corrupted
Redundant array of independent disks (RAID)
 Used to store duplicate data on multiple disks
Storage area network (SAN)
 Used to connect multiple storage devices on highspeed networks
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Using Database Systems in
Organizations
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Organizations need to process routine transactions
 Routine processing activities
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Pay employees
Send out bills to maintain a healthy cash flow
Send out a monthly newsletter
Pay suppliers for parts and raw materials
Information and decision support
 Valuable tool to support decision making
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Data Warehouses, Data Marts, and
Data Mining
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Data warehouse
 Holds important information from a variety of
sources
 Usually a subset of multiple databases
Data mart
 Small data warehouse
 Often developed for a specific person or purpose
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Data Warehouses, Data Marts, and
Data Mining (continued)
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Data mining
 Extracting information from a data warehouse or a
data mart
Business intelligence
 Business use of use data mining can help increase
efficiency, reduce costs, or increase profits
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Database Trends – Distributed
Databases
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Distributed database
Also called a virtualized database
 Actual data may be spread across several
databases at different locations
 Allow more users direct access at different user
sites
Replicated database
 Database that holds a duplicate set of frequently
used data
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Managing Databases – Database
Administration
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Database administrators are responsible for
 Overall design and coordination of the database
 Development and maintenance of schemas
 Development and maintenance of the data
dictionary
 Implementation of the DBMS
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Database Use, Policies, and Security
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End-user computing
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Development and use of application programs by
noncomputer-systems professionals
End-user computing issues
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What data can users read, update, or write in a
database?
What procedures are needed to guarantee proper
database use and security?
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Summary
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Data
 Organized into a hierarchy
Entity
 Generalized class of objects for which data is
collected
Database designers
 Can use a data model to show relationships among
data
Object-oriented model
 Stores data as objects
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Summary (continued)
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DBMS
 Group of programs used as an interface between a
database and application programs
Schemas
 Entered into the computer via a data definition
language (DDL)
Most organizations use a database system to
 Send out bills, pay suppliers
 Print paychecks
 Perform other routine transaction processing
activities
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