Personal information management

musicincurableΔιαχείριση Δεδομένων

31 Ιαν 2013 (πριν από 4 χρόνια και 4 μήνες)

126 εμφανίσεις

Chapter 07:

Database Systems

Succeeding with Technology, Third Edition

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, Third Edition

3

Objectives


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, Third Edition

Chapter Content


Basic Data Management Concepts



Organizing Data in a Database



Database Management Systems

4

Succeeding with Technology, Third Edition

Chapter Content


Using Database Systems in Organizations



Database Trends



Managing Databases

5

Succeeding with Technology, Third Edition

Basic Data Management Concepts


Database


A collection of data organized to meet users’ needs


Database management system (DBMS)


A group of programs that manipulate the database
and provide an interface between the database and
the user or the database and application programs


Database system


Comprised of database, DBMS, and application
programs

6

Succeeding with Technology, Third Edition

Basic Data Management Concepts


Some functions of a DBMS


Store important data such as phone numbers,
addresses, text, images, audio signals


Perform routine tasks such as preparing income tax
forms or produce paychecks for employees


Make better decisions by using information gathered
from databases and creating reports


Protect data from attacks and unauthorized access


7

Succeeding with Technology, Third Edition

Data Storage and Retrieval


Personal information management

(
PIM
) refers to
both the practice and the study of the activities
people perform in order to acquire, organize,
maintain, retrieve and use information items such as
documents (paper
-
based and digital), web pages
and email messages for everyday use to complete
tasks (work
-
related and not) and fulfill a person’s
various roles (as parent, employee, friend, member
of community, etc.)


Address Book


Email

8

Succeeding with Technology, Third Edition

Advantage of the Database approach
to data storage and retrieval


Standardization of data access


Reduced data redundancy


Easier modification and updating


Improved data integrity


Shared data and information resources

9

Succeeding with Technology, Third Edition

Basic Data Management Concepts

10

Succeeding with Technology, Third Edition

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


11

Succeeding with Technology, Third Edition

Data Management for Individuals

and Organizations


Without data and the ability to process it,
organizations would not be able to complete
most activities successfully


Generate reports to help achieve goals


Pay employees


Bills


Inventory


Scientific research

12

Succeeding with Technology, Third Edition

Hierarchy of Data


Field


A component of a database which contains a single item
such as name, number, or combination of characters that
describes some aspect of an object


Record


Collection of related fields that describe some object or
activity


File or table


Collection of related records


Database


Collection of integrated and related files or tables


13

Succeeding with Technology, Third Edition

Hierarchy of Data

14

Succeeding with Technology, Third Edition

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


The specific value of an attribute is called a data item


Key


Field in a record used to identify the record


Primary key



Uniquely identifies the record in a database file


A data anomaly such as a two people with the same name
can be resolved


15

Succeeding with Technology, Third Edition

Data Entities, Attributes, and Keys

16

Succeeding with Technology, Third Edition

Simple Approaches to Data Management


There are several ways to manage data


Software packages


Personal information managers


Phone numbers and addresses


Handheld devices


Home budget software


17

Succeeding with Technology, Third Edition

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)


Many modern databases are organization
-
wide,
containing much of the data for an entire
organization


18

Succeeding with Technology, Third Edition

The Database Approach to

Data Management

19

Succeeding with Technology, Third Edition

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?


20

Succeeding with Technology, Third Edition

The Relational Database Model


Purpose


To describe data using a standard tabular format


All data elements are placed in two
-
dimensional tables
called
relations


databases are best designed using small, logically
interconnected tables


reduce data redundancy


Joining



Combining two or more tables (connected or associated using
a
common element
-
field)


Selecting


Choosing data based on certain criteria (e.g. Getting only
those students who are on the cross
-
country team)

21

Succeeding with Technology, Third Edition

The Relational Database Model

22

Succeeding with Technology, Third Edition

Data Analysis


Evaluating data to identify problems with
content of database


Store good data


Non
-
redundant


Simple


Adaptable


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


23

Succeeding with Technology, Third Edition

Object
-
Oriented Databases


Use the same overall approach as objected
-
oriented
programming


Data and processing instructions are stored in the
database


Object
-
oriented database management system (OODBMS)


Offers the ability to reuse and modify existing objects


Some modern DBMSs incorporate object
-
oriented
capabilities in a relational database


Object
-
relational database


24

Succeeding with Technology, Third Edition

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


25

Succeeding with Technology, Third Edition

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


26

Succeeding with Technology, Third Edition

Overview of Database Types


Flat file


Has no relationship between its records


Used to store and manipulate a single table or file


stores each record as a line of text, and uses commas, tabs, or other
indicators within the line to separate the items


Comma
-
separated values (CSV)


File organizer


Goes beyond the capabilities of a flat file to store and/or retrieve data


Single User


Only one person can use the database at any time (e.g. Microsoft Outlook
and Quicken used to store and manipulate personal data)


Multiuser


Networked computer systems need multiuser DBMSs


Allow several people in an organization access the data and to see each
other’s changes


27

Succeeding with Technology, Third Edition

Overview of Database Types

28

Succeeding with Technology, Third Edition

Overview of Database Types


General
-
purpose database


Can be used for a large number of applications


Special
-
purpose database


Designed for a limited number of applications or to
serve a specific need


Open
-
Source database systems


PostgreSQL, MySQL


29

Succeeding with Technology, Third Edition

Overview of Database Types

30

Succeeding with Technology, Third Edition

Database Design


Field 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


31

Succeeding with Technology, Third Edition

Database Design


Record and table design


Record: A collection of related fields


Table: A collection of related records


In any database, you must


Identify the exact fields for each record


Identify the types of records for each table


Tables can be organized in many ways

32

Succeeding with Technology, Third Edition

Database Design

33

Succeeding with Technology, Third Edition

Database Design


Input and output interface design


Creating effective interfaces is a powerful design
feature


Designers can create easy
-
to
-
understand forms


After data is entered, the database can go
automatically to the next field without requiring
action by the user


Reports (A view of just a portion of a database
records and/or fields) and other outputs can also
be powerful and packed with information

34

Succeeding with Technology, Third Edition

Database Design

35

Succeeding with Technology, Third Edition

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


System designers are increasingly using the Web
as the front end to database systems

36

Succeeding with Technology, Third Edition

Using Databases with Other Software

37

Succeeding with Technology, Third Edition

Data Analysis


A process that involves evaluating data to
identify problems with the content of a database

38

Succeeding with Technology, Third Edition

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


39

Succeeding with Technology, Third Edition

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 used to
define and describe data and data relationships


Data dictionary


Detailed description of all data used in the database


40

Succeeding with Technology, Third Edition

Creating and Modifying a Database

41

Succeeding with Technology, Third Edition

Creating and Modifying a Database


Typical uses of a data dictionary


Provide a standard definition of terms and data
elements that can be referenced by programmers,
database administrators, and users to maintain data
integrity


Assist programmers in designing and writing
programs


Simplify database modification


42

Succeeding with Technology, Third Edition

Creating and Modifying a Database


The data dictionary helps achieve the advantages
of the database approach by


Reducing data redundancy


Increasing security


Speeding program development


Simplifying modification of data and information

43

Succeeding with Technology, Third Edition

Updating a Database


Databases are updated by adding, modifying, or
deleting records


Essential to maintain data accuracy and integrity


Front
-
end applications can be used to enter changes
which are then transferred to the database

44

Succeeding with Technology, Third Edition

Updating a Database

45

Succeeding with Technology, Third Edition

Manipulating Data and Generating Reports


Data manipulation language (DML)


Allows users to


Access, modify, and make queries about data contained in
the database


Generate reports


Query by example (QBE)


Makes manipulating databases much easier and
faster


Structured Query Language (SQL)


Standardized data manipulation language (
vocabulary
used to manipulate data)


46

Succeeding with Technology, Third Edition

Manipulating Data and Generating Reports

47

Succeeding with Technology, Third Edition

Database Backup and Recovery


Database backup


A copy of all or part of the database


help to minimize losing backup data companies are beginning to use
GPS and RFID


Database recovery


Returning database to original, correct condition if it has crashed or
has been corrupted


Disaster recovery: providing a plan for how to bring systems back
online after an emergency


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


48

Succeeding with Technology, Third Edition

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


49

Succeeding with Technology, Third Edition

Data Warehouses, Data Marts,

and Data Mining


Data warehouse


Large database that holds important information
from a variety of sources


Usually a subset of multiple databases maintained by
an organization or individual


Data mart


Small data warehouse


Often developed for a specific person or purpose



50

Succeeding with Technology, Third Edition

Data Warehouses, Data Marts,

and Data Mining


Data mining


Process of extracting information from a data
warehouse or a data mart


Business intelligence


In a business setting, use data mining can help
increase efficiency, reduce costs, or increase profits


51

Succeeding with Technology, Third Edition

Data Warehouses, Data Marts,

and Data Mining

52

Succeeding with Technology, Third Edition

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


Master database file: database that records the existence of all other
databases and the location of those database files and records the
initialization information for database


Transaction database file: comprises a unit of work performed within a
DBMS against a database, and treated in a coherent and reliable way
independent of other transactions



Replicated database


Database that holds a duplicate set of frequently used data


53

Succeeding with Technology, Third Edition

Database Systems, the Internet,

and Networks


Databases are typically used to organize and deliver
Web data and information


Invisible to the user


The Web is the front end


All requests to the database are made through the
Internet


Internet access to databases allows collaboration


Security is a concern


According to the text, some security experts believe that
up to 40 percent of Web sites that connect to corporate
databases are susceptible to letting hackers take
complete control of the database

54

Succeeding with Technology, Third Edition

Trends


Distributed Databases

55

Succeeding with Technology, Third Edition

Database Systems, the Internet,

and Networks

56

Succeeding with Technology, Third Edition

Visual, Audio, Unstructured,

and Other Database Systems


Organizations are finding needs to store visual and
audio data


Music companies


Store and manipulate sound from studios


Databases can be used to correct pitch errors in singing


Drug companies


Analyze large numbers of visual images


Law enforcement


Database of fingerprints


Unstructured database


Contains data that is difficult to place in traditional systems

57

Succeeding with Technology, Third Edition

Visual, Audio, Unstructured,

and Other Database Systems

58

Succeeding with Technology, Third Edition

Database Administration


Database administrator


A skilled and trained computer professional who directs all
activities related to an organization’s database, including
providing security from intruders


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


System and user documentation


User support and training


Overall operation of the DBMS


Testing and maintaining of the DBMS


Establishing emergency and recovery procedures


59

Succeeding with Technology, Third Edition

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?


When can data be transferred from small computer systems
to the mainframe or server? (Uploading)


When can data be transferred from the mainframe or server
to personal computers or smaller systems? (Downloading)


What procedures are needed to guarantee proper database
use and security?

60

Succeeding with Technology, Third Edition

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


61

Succeeding with Technology, Third Edition

Summary


Data Analysis


Uncovers problems with the content of a database


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


62

Succeeding with Technology, Third Edition

Summary


Distributed database


Data is spread across several databases at different locations


Database systems often work in conjunction with
the Internet and networks


Many organizations need specialized databases


Audio, visual storage


Database administrators


Manage the database


Are responsible for database use, policies, and security

63