chapter 1a db environment(1)

8/11/2019 Chapter 1A DB Environment(1)

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Chapter 1A

The Database Environment


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Objectives

Learn what a database is, the different types and why they are

valuable tools for decision making

How databases evolved from basic file systems

Flaws in the file system data management

Main components of a database system

Main functions of a database management system (DBMS)

Advantages/Disadvantages of the database approach

Importance of database design

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Why Study Databases? Everybody is doing it.

Organizations have large masses of data that are almost

impossible to manage without database systems. Excel spreadsheets are not capable of managing data.

Many jobs demand an understanding of how databases

work and interact with other applications.

Most employees dont understand how the data isorganized and how to obtain the data necessary for even

the most simple reports.

3Database Systems, 10th Edition


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Pre-Database Systems: File Mgmt

Payroll System

ClassScheduling

System

Parking System

Note: each system contains a definition of data5


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Database Systemhardware, software, people, procedures, database DBMSa set of programs that manages the database

Databasedata, metadata


A Database System

Employees

Classes

Parking

Students


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The Database System: Components Five major parts of a database system:

Hardware

Computers, network, cables

Software DBMS, user programs, query languages, support system (OS)

People

Users, programmers, administrators, operators

Procedures

Use, location, changes, design, contingency plans

Database

Data and meta-data

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A Database - Defined A database is a self-describing collection of integrated

files; the database contains a description of itself.

There are many acceptable definitionsI think this one isthe best.

Note that the definition does not include the following:

Elimination of redundancy

Multiple users

Efficiency, low-cost, fast access, etc.

Mention of data structures or models

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Database Management System A set of programs that manages the database

DBMS is the intermediary between the user, userprograms, and the database

Database structure stored as file collection

Can only access files through the DBMS

DBMS enables data to be shared DBMS integrates many users views of the data



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Database System EnvironmentUsers & Programmers

Application Programs/Queries/SQL

DBMS

Data DefinitionMeta-Data

Stored Data

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Software to ProcessQueries/Programs

Software to AccessStored Data


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Database Approach: Advantages

Minimal data redundancy

Improved data sharing

Uniform security, privacy & integrity controls

Better data integration Data accessibility and responsiveness

Enforcement of standards; data consistency

Improved decision making

Ease of application development

Reduced program maintenance

Data independence



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Database Approach: Disadvantages

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DBMS software is expensive; may require more hardware

Organizational conflict

Increased vulnerability due to

centralization or decentralization

DB systems are very complex

New, specialized personnel


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Importance of Database Design

This very simple design causes all sorts of problems. Can

you spot them?

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The data must be separated to reduce the redundancy.


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A Good DesignWeve separated the

data but there are still

problems

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Where does the

grade belong?


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A Better DesignStudents

Courses

Instructors

Grades

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Display GPA and Total Hrs for Jane Smith.Display Course#, Course Description and

Grade for Arthur Lee.

Display the names of all students

who have taken CIS-360.Display the Student ID, Student Name, Grade, Instructor

Name for all students that completed ACC-231.

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