Chapter 7: Database Systems

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Chapter 7 Database Systems

• Succeeding with Technology Second Edition

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Objectives

• Understand basic data management concepts
• Describe database models and characteristics
• Discuss the different types of database
  management systems and their design and use by
  individuals and organizations

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Objectives (continued)

• Describe how organizations use database systems
  to perform routine processing, provide
  information and decision support, and how they
  use data warehouses, marts, and mining
• Discuss additional database systems, including
  distributed systems and Web-based systems
• Describe the role of the database administrator
  (DBA) and database policies and security practices

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Basic Data Management Concepts

• 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

• 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

• 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

• 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
• Uniquely identifies the record

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The Database Approach to Data Management

• 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

• Questions to be asked when building a database
• What data is to be collected and at what cost
• What data is to be provided to which users when
  appropriate
• How is the data to be arranged so that it makes
  sense
• Where is the data to be physically located
• Who is responsible for maintaining an accurate
  database system

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The Relational Database Model

• 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

• 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

• 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

• Database size or amount
• Depends on the number of records or files in the
  database
• Volatility of data
• Measure of the changes typically required in a
  given period of time
• Immediacy
• Measure of how rapidly changes must be made to
  data

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Database Management Systems

• 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

• 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)

• General-purpose database
• Can be used for a large number of applications
• Special-purpose database
• Designed for a limited number of applications
• Open-Source database systems
• PostgreSQL, MySQL

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Database Design

• 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

• 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

• 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

• 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)

• 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

• Data manipulation language (DML)
• Allows users to
• 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

• 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
  high-speed networks

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Using Database Systems in Organizations

• Organizations need to process routine
  transactions
• Routine processing activities
• 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

• 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)

• 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

• 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

• 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

• End-user computing
• Development and use of application programs by
  noncomputer-systems professionals
• End-user computing issues
• 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

• 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)

• 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