2. Contents
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DDDaaatttaaa
Definition:
A collection of raw facts andfigures is called data. Theword Rawmeans
that thefacts have not yet been processedto get their exact meaning .Datais
collected from different sources. It is collected for different purposes. Datamay
consist of numbers, characters, symbols or pictures etc.
EEExxxaaammmpppllleeesss ooofff DDDaaatttaaa
1. When students get admission in college or universities, they have tofill out
an admission form. Theform consists of raw facts about thestudents.
Theseraw facts are student’s name, fathername, address etc.
Thepurpose of collecting datais tomaintain therecords of students during
study period in college or university.
2. During census, government of Pakistan collects the dataof all citizens.
Government stores this datapermanently touse it for different purposes
at different times.
3. Different organizations conduct surveys toknow theopinion of the people
about their product. In these surveys, people express their ideas and
opinions about different issues. Theseideas and opinion of thepeople are
3. storedad data. Theorganizations usethis data forthe improvement of
their products.
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Datamay be of thefollowing types:
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Numeric dataconsists of numeric digits form 0 to9 like10, 245or 5.
Thenumeric type of data may either be positive or negative.
AAAlllppphhhaaabbbeeetttiiiccc DDDaaatttaaa:::
Alphabetic data consists of alphabetic letters from A to Z, a toz and
blank space e.g. “IT series”, “computer”, and“Islam”etc.
AAALLLPPPHHHAAANNNUUUMMMEEERRRIIICCC DDDAAATTTAAA:::
Alphanumeric data consists of numericdigits (0 to9), letters
(A to Z) andall special characters like +, %and @ etc. like “87%”, “$300” and
“H#17”.
IIImmmaaagggeee DDDaaatttaaa:::
This type of Dataincludes charts, graphs, pictures, and drawings. This
form of data is more comprehensive. It can be transmittedas a set of bits.
AAAuuudddiiiooo DDDaaatttaaa:::
Soundis a representation of audio. Audiodata includes music, speech
or any typeof sound.
VVViiidddeeeooo DDDaaatttaaa:::
Videois set of full-motion images played at a high speed. Videois used
to display action and movements.
4. IIInnnfffooorrrmmmaaatttiiiooonnn
Theprocessed data is called information. Information is an organized and
processed from of data. It is moremeaningful than data andis usedfor making
decisions. Datais used as input for theprocessing and information is theoutput
of this processing. This information can be used again in some otherprocessing
and will be considered as datain that information.
ForExample, themarks of the student in different subject is thedata. To
calculate totalmarks, themarks of different subjects are usedas data and a total
mark is the information. Now, tocalculate theaverage marks of the student, this
information will be processed again. In this processing, theinformation is usedas
data andaverage marks will be theinformation.
EEExxxaaammmpppllleeesss ooofff IIInnnfffooorrrmmmaaatttiiiooonnn:::
Some examples of information are as follows:
111... In colleges and universities, theraw facts about students arestoredon
admission forms. If wewant tofind out a list of all students wholivein
Faisalabad, wewill apply someprocessing and will be called information.
222... Thedata storedin census is usedtogenerate different type of information.
Forexample, government can useit to findtotal numberof graduates or
literacy rate in country etc. This information can be obtained by processing
storeddata. Government can usethis information totakeimportant
decisions toimprove literacy rate.
333... An organization can usetheopinion of thepeople as data andprocess it to
generate information of its interest.
Forexample, it can know that how manypeople of the country are satisfied
with thequality of its product andhow manyare unsatisfied. The
organization can usethis information for theimprovement of its product.
5. MMMeeetttaaadddaaatttaaa
Metadatacan be defined as dataabout data. It is usedtodescribe the properties
and characteristics of someother data. Metadatadescribes thesize, format and
other characteristics of data. It alsoincludes the rules andconstraints about data.
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Traditional or simple file processing is the first computer-basedmethodto
handle business application. In the past, manyorganization storeddata in files on
tape or disk. The datawas managedusing file-processing system. In atypical file
processing system, each department in an organization has its own set of files.
Thefiles are designed especially for their own applications. Therecords in one
file are not related totherecords in any other file.
Business organizations have usedfile-processing system formanyyears. But this
system has manydisadvantages.
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sssyyysssttteeemmm:::
someimportant disadvantages of file processing system
are as follows:
DDDaaatttaaa RRReeeddduuunnndddaaannncccyyy aaannnddd IIInnncccooonnnsssiiisssttteeennncccyyy:::
In file processing system, thesamedatamay be duplicated in several files.
Supposethere are twofiles “students” and“Library”. Thefile “students”contains
theRoll No, name address andtelephone number andother details of all
students in acollege. The file “Library” contains theRoll No and nameof those
students whoget abook from library along with theinformation about the
rented books. Thedata of onestudent appears in twofiles. This is known as data
redundancy causes higher storage.
Thesituation can also result in datainconsistency. Inconsistency means that two
6. files may contain different data of the samestudent.
Forexample, if theaddress of a student is changed, it must bechanged in both
files. There is a possibility that it is changed in the“students” fileandnot from
“Library” file. Thedata become inconsistent in this situation.
DDDaaatttaaa IIIsssooolllaaatttiiiooonnn:::
Thedata in file processing system is storedin various files. It becomes very
difficult towrite new application programs toretrieve theappropriate data.
Supposethat student’s emails are storedin “Students” fileand fee information is
storedin “Fee” file. The datafrom both files is required tosend an email message
to inform a student that thedataforfee payment is over. In file processing
system, it is difficult togenerate such typeof list from multiple files.
IIInnnttteeegggrrriiitttyyy PPPrrrooobbbllleeemmmsss:::
Integrity data reliability and accuracy of data. Thestoreddata must
satisfycertain types of consistency constrains.
Forexample, Roll No and Marks of students shouldbenumericvalue. It is difficult
to apply theseconstrains on files in file processing system.
PPPrrrooogggrrraaammm DDDaaatttaaa DDDeeepppeeennndddeeennncccyyy:::
program datadependency is a relationship between datain files
and program required toupdateand maintain thefiles. Application programs are
developed according toa particular file format in file processing system. If the
format of file is changed, theapplication program also needs tobe changed
accordingly.
ForExample, if there is change in thelength of postalcode, it requires changed in
theprogram. Thechanges may be costly toimplement.
AAAtttooommmiiiccciiitttyyy PPPrrrooobbbllleeemmm:::
An operation on data may consist of different steps. A collection of
all steps required torequire completing a process is known as transaction. The
atomicity means that either one transaction shouldtake place as a whole orit
shouldnot take place at all. Suppose a userwants totransfermoney from
7. account A toaccount B. this process consists of twosteps:
Deduct themoney from account A
Add themoney to account B
Suppose that thesystem fails when thecomputerhas performed thefirst step.
It means that theamount has been deducted from account A but has not been
added to account B. this situation can make datainconsistent. File processing
system does not provide thefacility toensureatomicity of data.
SSSeeecccuuurrriiitttyyy PPPrrrooobbbllleeemmmsss:::
File processing system does not provide adequate security on data. In
somesituations, it is required toprovide different types of access to datafor
different users.
PPPrrrooogggrrraaammm MMMaaaiiinnnttteeennnaaannnccceee:::
The programs developed in file processing system are difficult to
maintain, mist of the budget may be spent on maintenance, it makes it difficult
to develop new applications.
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