Chapter 7: Database Systems Succeeding with Technology: Second Edition

Succeeding with Technology 2 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

Succeeding with Technology 3 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

Succeeding with Technology 4 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

Succeeding with Technology 5 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

Succeeding with Technology 6 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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8 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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10 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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Succeeding with Technology 13 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

Succeeding with Technology 14 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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Succeeding with Technology 17 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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Succeeding with Technology 20 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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Succeeding with Technology 22 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

Succeeding with Technology 23 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

Succeeding with Technology 24 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

Succeeding with Technology 25 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

Succeeding with Technology 26 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

Succeeding with Technology 27 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

Succeeding with Technology 28 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

Succeeding with Technology 29 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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Succeeding with Technology 31 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

Succeeding with Technology 32 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

Succeeding with Technology 33 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

Succeeding with Technology 34 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

Succeeding with Technology 35 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

Succeeding with Technology 36 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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Succeeding with Technology 38 Database Trends – Distributed Databases D istributed 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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Succeeding with Technology 40 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

Succeeding with Technology 41 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?

Succeeding with Technology 42 Summary Data  Organized into a hierarchy E ntity  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

Succeeding with Technology 43 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