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IT for DBA


IT for DBA is a guide for the students of Diploma in Business Administration by Technical Board. This book is written by Inqilab Ruknuddin Patel of RIC: Ruknuddin Institute of Computer

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									    RIC- Ruknuddin Institute of Computer (Management &IT)               IT for DBA-1   2

Q1: What is office automation?
    “Office automation means using self acting or automatic machines for performing
    office work. The automatic office was new technology such as computer,
    electronic typewriter, internet etc for office automation.”
    Office automation encompasses five major technologies.
    Information in numeric form usually calculated by computer is called “Data
    Processing”. Data processing is mathematical and logical manipulation of data.
    Information in text form (words & numbers) is called word processing. Creating,
    formatting, printing documents like letter, circular memo, and reports etc is called
    “Word Processing”
    Graphics is the technology in which information are converted into chart graphs
    and are displayed on screen.
    An imaging technology transforms graphical images (photographs, picture, and
    drawings) into machine readable form on computer screen.
    The processing of information in the form of spoken words is called “Voice”

Q2: What is information processing cycle?
    “During data processing data is cycled through five stages. These stages are
    called INFORMATION PROCESSING CYCLE. The stages of information
    processing cycle are below.

    Prepared by Inqilab Patel                     Typed by Shoaib Anwer Qambrani
RIC- Ruknuddin Institute of Computer (Management &IT)                IT for DBA-1   3

Input is the first stage of information processing cycle in which data is entered in
Processing is the work don on data to obtain result (information). These are two
types of processing.
Data processing
Data processing is mathematical and logical manipulation of data.
Word processing
Creating, formatting, printing documents like letter, circular memo, and reports
etc is called “Word Processing”
Output is the third stage and this stage information (result) of processing is
This is the fifth stage in which information is communicated to other people.
In this stage information are stored and stored information are retrieved (read
and write).



Prepared by Inqilab Patel                       Typed by Shoaib Anwer Qambrani
    RIC- Ruknuddin Institute of Computer (Management &IT)                IT for DBA-1   4

Q3: Why office is called information center?
Ans Office is called information center because it is the place where information is
    recorded, copied, storied, retrieved (read and write) and communicated. For
    example in office of a company all information’s about employees, clients,
    suppliers, production, purchases, sell, profit, loss, expense are kept.

Q4: Describe technologies used in office?
Ans Technology is the knowledge of the process and technologies that transforms the
    abstract ideas of scientists into a concrete reality. The new technology has
    changed office work with the keep of invention of type writer, telephone, fax
    machine, computer and internet etc.
    The typewriter is a machine which is used to create documents with a speed of
    almost 40 words per minute (WPM) before invention of typewriter all documents
    are written without help of any machine. The speed of writing was very slow
    (about to WPM). Information moves around in and out of office at slow speed.
    Typewriter has increased the speed of document creation. The keyboard has
    now standard sequence of letters. Now electrical and electronic type writers have
    invented. Which also increase speed of document creation.
    Alexander Graham Bell invented telephone in 1876 before invention of telephone
    communication was done orally or by letters or by telegraph.
    Oral and letter communication was slow. The greater the distance, the largr it
    took to get there while in telephone MORS CODE is used which is very
    complicated. Telephone made voice communication very easy and fast. No
    matter, what the distance any one can talk with other, without any delay of time.

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RIC- Ruknuddin Institute of Computer (Management &IT)              IT for DBA-1   5

Fax machine is like a photocopies machine which is attached with telephone line.
Fax machine makes documents exchange very fast and reliable to send a
document it is inserted in fax machine then number of reception is divided. The
fax machine of reception creates a photocopy of the document. Graphics,
images, diagrams, text, agreement and other documents can be sent by fax. Fax
machines are basically electronic document deliver system that combines
scanner and text or graphic images recorded on paper to electrical impulses that
can be transmitted over telephone ( or other) network. Fax machine may be
either analog or digital; the digital machine are normally typically faster sending
faxed documents normally requires a relatively fast fax modem, about 9600 bps
or greater. But even at these speeds, the clarity of some faxed documents may
not measure up to the original or even to a photocopy of it. How ever the quality
of facsimile output is steadily increasing and the latest generation of fax machine
utilizes las4r technology for both higher resolution and higher sped output.

The word computer is derived from a word “Compute” which means “to
calculate”. Computer may be defined as:
“A computer is an electronic data processing machine that accepts data and
instructions (programs) as input, processes the data according to given
instructions and produces information as output.”
      Computer can also be defined as:
“A computer is an electronic data processing machine, which works under control
of stored programs, accepts the data, processes the data according to
instructions (programs) and gives information (result).”
      From the beginning man tried to invent a device that can help him in
calculations about 3000 years BC, Chinese developed the first calculating

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machine named Abacus or Soroban. In early century John Napier invented
cardboard multiplication calculator. In 1642 Pascal invented mathematical adding
machine. Charles Babbage, the father of computer, designed “Difference Engine”
in 1822 the first business computer was installed in 1954. In 1977 first micro
computer was invented by Apple Company.
Now a day all calculation and documentation work of an office is done on
computer like invoicing, data base management, stock control, payroll, reports,
circulars, memos etc.
A global network connecting millions of computers. More than 100 countries are
linked into exchanges of data, news and opinions. Unlike online services, which
are centrally controlled, the Internet is decentralized by design. Each Internet
computer, called a host, is independent. Its operators can choose which Internet
services to use and which local services to make available to the global Internet
community. Remarkably, this anarchy by design works exceedingly well. There
are a variety of ways to access the Internet. Most online services, such as
America Online, offer access to some Internet services. It is also possible to gain
access through a commercial Internet Service Provider (ISP).
Electronic mail or ``e-mail'' does not require detailed explanation, since its basic
concepts are identical to those of traditional surface mail: there is a sender who
sends some written message to one or more addressees with the help of a
computer program. Although the message is sent directly to a certain computer,
it usually goes through a number of transferring computers and this may take
some minutes or even one or two hours if there is a lot of international traffic on
the net. For the sake of convenience the subject and date of the message is
indicated in the header together with the e-mail address of both the sender and

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    the recipient. For technical reasons the e-mail header may also contain some
    additional information referring to the route or the content of the message.
    E-mail addresses have a rigid structure that indicates the user's name on the net
    and the server computer that offers the mailing services. A typical e-mail address
    looks like this:    QAMSAN@GMAIL.COM

    Electronic commerce, commonly known as (e-shopping) or e-commerce consists
    of the buying and selling of products or services over electronic systems such as
    the Internet and other computer networks. The amount of trade conducted
    electronically has grown extraordinarily with widespread Internet usage. The use
    of commerce is conducted in this way, spurring and drawing on innovations in
    electronic funds transfer. Electronic commerce that is conducted between
    businesses and consumers, on the other hand, is referred to as business-to-
    consumer or B2C. This is the type of electronic commerce conducted by
    companies such as Online shopping is a form of electronic
    commerce where the buyer is directly online to the seller's computer usually via
    the internet. There is no intermediary service. The sale and purchase transaction
    is completed electronically and interactively in real-time such as for
    new books. If an intermediary is present, then the sale and purchase transaction
    is called electronic commerce such as

Q5: Write down the methods of documents creation?
Ans:       Methods of Documents Creation
    Sufficient wide margin should be left for corrections and addition of the officer or
    authority. When many correction and addition have been made in rough draft
    then a clean copy of the amended draft should be prepared. A typed rough draft
    can range from of word almost mail able to almost unintelligible. Its effectiveness

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    RIC- Ruknuddin Institute of Computer (Management &IT)                IT for DBA-1   8

    as a form of word origination is directly related to each author’s definition of the
    word “rough”

    Creating document by typing at keyboard is called keyboarding. The keyboard is
    the most common input device. The alphabetic numeric and special symbol keys
    are arrange on a typewriter or computer. The keys marked with arrows are used
    to more the CURSOR up, down, left, and right. The monitor is like television
    screen is connected with computer, which display the data typed with help of
    keyboard. The data can be checked and mistakes corrected before the help
    computer does processing. The ENTER key is also used to load the data into
    RAM for processing.

    The fastest and most efficient means of documents is machine dictation. In this
    method the author responds dictation a document record on machine when the
    secretary isn’t present. If the author is interrupted during dictation, the recording
    machine is simply turned off for a moment and the secretaries the dictation while
    listening to a playback of it.
    Documents produced by dictation, like any document generated in an office, go
    through cache step of the information processing cycle. The type of equipment is
    used for the dictation can b thought of as part of the method of input. The
    transcribed, finished documents are the output in hard copy form. On some
    dictation equipment of a document can add words to the middle of a document.
Q6: What is voice storage media?
    Voice storage media is equipment on which voice dictation is stand. The words
    are stored voice until a transcriptionist listens to them and prepare the final

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document. Dictation machines may differ from each other in media, or materials,
they use for recording. There are many kinds of voice storage media for
example, cassette tapes.
Some dictation system use recording media that can be easily detached from the
machines and used for other dictation or transcription. These are called discrete
media. The most popular discrete media are cassette one advantage of discrete
media is that they can be saved in case anyone needs to listed to them again
later because they can be detached and used on other machines discrete media
allow secretaries to handle rush transcription jobs with maximum speed . there
are two basic kinds of discrete voice storage media.
Magnetic Media
Inscribed Media
Magnetic media are usually thin, narrow tapes that record the author’s voice by
mean of electric impulse and magnetism. Since magnetic tapes can be erased,
they are quite economical. They are also convenient on some magnetic media an
author who wants to make a change in a dictation document can rewind the tape,
erase the words that should be deleted; and dictate new words in their place.
Once the document on magnetic tape has been transcribed, the tape can be
completely erased and reused.
Cassette tapes designed for dictation are better at recording the human voice
than the tapes, which used for entertainment. They are also engineered to
eliminate extraneous room noise, and this raises the sound quality.
Although most modern voice storage media are magnetic, you should also be
familiar with inscribed media. These are media that can not be erased or
renewed some dictation machines record the author, flexible plastic belt, a few

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    inches wide and a foot or two in diameter. These belts are a form of inscribed
    media mainly authors who want permanent recordings of their spoken words, use
    the belts. Inscribed media also include cassettes cylinders, and disks. (It is
    possible to prevent erasure on cassettes, thus making them inscribed media).
    Although belts and other inscribed media are no longer being manufactured, they
    may still be found in some offices..
Q7 What is media compatibility?
    Media compatibility means considering that a media is useable with equipment or
    not. In order to transcribe recorded dictation, it may b recorded on a media that is
    compatible with, or matches, other transcription equipment. On can’t transcribe
    dictation that was recorded on a micro cassette if his transcription equipment is
    part of an endless loop system of if it accepts only inscribed belts. Even if his
    transcription machine accepts cassette, the cassette must b right size.
    For example a unit that accepts only standard cassettes would be unless in
    transcribing, dictation from a mini cassette or micro cassette.
Q8 What are printers?
    Printer is an output device which prints results of processing on paper. The
    output or printout of document is called hardcopy. The printer is the device that
    produces the finished document after it has been keyboard and after any
    corrections and revisions have been made. There are two basic categories of
          Impact printers
          Non-Impact printers
    The printers which print by striking type against paper is called impact printer.
    They can produce carbon copies of documents on an impact printer the type

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   element may be by directional, which means it moves first left to right and then
   from right to left unlike a typewriter. It can do this because the text has already
   been keyboarded.
   Impact printers that print one character at a time are called character printers.
   These printers, which may or may not be by directional, are used for letters and
   other kind of output that must be of high quality. The type element on a character
   printer includes upper and lower case letters. Type elements are available in
   peculate, and micro size (15 characters to an inch) as well as in many typefaces.
   For example, daisy wheel, thermal, dot matrix, line printers.
   Non-impact printer does not depend on the impact of metal on paper. In fact no
   physical contact at all occurs between the printing mechanism and the paper.
   The most popular non-impact methods today utilize thermal transfer, ink-jet. They
   can not produce carbon copies as impact printers can, and some require special
   paper, but they are capable of producing even higher quality output.

Q9 write a note on DAISY WHEEL PRINTER?
   Daisy wheel printer are some times called letter quality printer because they are
   often used to produce attractive correspondence. The D.W.P is a flat circular
   device made of metal with character embossed on it. As this wheel spins at a
   very high speed the hammer hits the specific character against the ribbon which
   presses against the paper.

Q10 write a note on DOT MATRIX PRINTER?
   Any printer that produces character made up of dots using a wire pin printed
   head. The quality of output from a dot matrix printer depends largely on the

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   number of dots in the matrix, which might be low enough to show individual dots
   or might be high enough to approach the look of fully formed characters. Dot
   matrix printers are often categorized by the number of pins in the printer head
   typically, 9 or 24.

Q11 write a note on PLOTTER?
   Plotter is a special output device, which is used to produce high quality, perfectly
   proportional hard copy output. Plotters are designed to produce large drawings or
   images such as construction plans for buildings or blue prints for mechanical
   devices. Plotters have been used in automotive and aircraft design, topological
   surveys, architectural layouts and other similar complex drafting jobs. A plotter is
   composed of a pen, a move-able carriage, a drum and a holder for chart paper.
   Both the pen and the paper can move up and down and back and forth. This
   permits very detailed drawings. Some plotter having colored pens can make
   colored drawings also. There are two types of plotters, which are as follows:
          1. Drum Plotter
          2. Flatbed Plotter
   On the drum plotter, the pens, and the drum move concurrently in different axes
   to produce the image. Drum plotters are used to produce continuous output, such
   as plotting earthquake activity, or for long graphic output, such as structural view
   of a skyscraper.

   On some flatbed plotters, the pen moves in both axes while the paper remains
   stationary. However, on most desktop plotters, both paper and pen move
   concurrently in much the same way as on drum plotters.

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Q12 : write a note on LASER PRINTERS?
    An electro photographic printer that is based on the technology used by
    photocopiers. A focused laser beam and a rotating mirror are used to draw an
    image of the desired page on a photosensitive drum. This image is converted on
    the drum into an electrostatic charge, which attracts and holds toner. A piece of
    electro statically charged paper is rolled against the drum, which pulls the toner
    away from the drum and onto the paper. Heat is then applied to fuse the toner to
    the paper. Finally, the electrified charge is removed from the drum and the
    excess toner is collected. By omitting the final step and repeating only the toner
    application and paper handling steps, the printer can make multiple copies.

Q13 write a note on Thimble Printer?
Ans Thimble Printer
    A type of printer that uses a typing element known as thimble, which contains a
    full set of alphanumeric characters that are pressed through an ink ribbon onto
    the paper. A thimble printer acts much like many typewriters do. These printers
    were popular before inkjet and laser computer printers became popular;
    however, they are no longer used by computer users today.
Q14 Write a note on Line printers?
    Any printer that prints one line at one time, as opposed to one character at a time
    or one page at a time. Line printers typically produce the 11 by 17 inch
    “computer” printout. They are high speed devices and are often used with
    mainframes, minicomputers, or networked machines rather than with single user
    system. Types of line printers include chain printers and band printer. The line
    printer is a form of high speed impact printer in which one line of type is printed
    at a time. They are mostly associated with the early days of computing, but the

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    technology is still in use. Print speeds of 600 to 1200 lines-per-minute
    (approximately 10 to 20 pages per minute) were common. These printers can be
    divided into two types.
      i.   Drum Printer
     ii.   Chain Printer

    Drum Printer
    In a typical drum printer design, a fixed font character set is engraved onto the
    periphery of a number of print wheels, the number matching the number of
    columns (letters in a line) the printer could print. The wheels, joined to form a
    large drum (cylinder), spin at high speed and paper and an inked ribbon are
    stepped (moved) past the print position. As the desired character for each
    column passes the print position

    Chain (train) Printer
    Chain printers (also known as train printers) placed the type on moving bars (a
    horizontally-moving chain). As with the drum printer, as the correct character
    passed by each column, a hammer was fired from behind the paper. Compared
    to drum printers, chain printers had the advantage that the type chain could
    usually be changed by the operator. By selecting chains that had a smaller
    character set (for example, just numbers and a few punctuation marks)

Q13 write a note on Inkjet printer?
Ans Inkjet printer
    An Inkjet printer is a printer for computers. It uses special ink to print on the
    paper. Another type of printing technology is the Laser printer. Usually, inkjet
    printers are used by people who print very little. The ink comes in special ink
    cartridges, which can be very expensive and uneconomical. Also, the ink in the

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    cartridge may dry up. This means that a new cartridge is needed. Many
    professionals use inkjet printers to print on very large surfaces (up to 5m width).
    These printers usually do not use cartridges, but have a continuous supply of ink
    that could last for a long time. Inkjet printers need special paper. This paper has
    been treated so that the ink does not smear.

Q13 write a note on thermal transfer printer?
Ans A thermal transfer printer is a printer which prints on paper (or some other
    material) by melting a coating of ribbon so that it stays glued to the material on
    which the print is applied. It contrasts with Direct Thermal printing where no
    ribbon is present in the process. The printers use a fixed width thermal print
    head, pressing onto a paper or plastic label, over a driven rubber roller called a
    platen. Between the print head and the label is sandwiched a very thin thermal
    transfer ribbon (or sometimes called "foil"), which is a polyester film which has
    been coated on the label side with a wax, wax-resin or pure resin "ink". Almost all
    thermal label printers use special internal description languages to allow the label
    to be laid out inside the printers' memory prior to printing.
Q14: What is reprographics
    The process by which one or more copies of graphic or written material are
    produced is called reprographics. Reprographic covers several different
    technologies, including photocopies, phototypesetting, offset printing, and
    Office may use several methods to produce copies of documents. Some
    methods are used equipment such as typewriter or printer, photocopiers,
    duplicators, and printers.

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Repetitive printing simply means printing more than one original hardcopy. One
using an electric typewriter, one will have to type the original document over and
over again to generate several original copies. Of course with automated word
processing and microcomputers using word processing software, user can simply
command the printer to prints many hard copies as he need.

Carbon paper was introduced soon after the type writer was invented. For
deadest it remained the only method if reprographics besides hand copying. With
the advent of high-speed impact printers, carbon paper may return to favor again.
It is fast and economical mean of creating a small number of copies at a time.
Some copy sets do not have carbon; instead, the paper is chemically treated so
that characters print on the original carry through to the copies. These sets are
sometime referred to as “NCR” a pack, NCR stands for “No Carbon Required”.

A duplicator is a machine that makes copies using a “Master” spirit stencil and
offset are methods of duplicating fairly numbers of copies, from 250 to several
Photocopying is the most common method of reprographics used in offices
today. Since the 1960s, photocopiers have been used to produce more than 234
million copies very day. Photocopiers do not require the preparation of a neither
master, nor do they require special training to operate.
The word facsimile means “An exact reproduction or copy of something”. To this
extent, all photocopiers are facsimile. However, in reprographics facsimile refers

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    to a special process by which a copy of a document or graphics illustration is
    sent electronically from one machine to another via telephone lines or other
    electronic means. The machines may bee the same building or great distance
    may separate them. News agencies have used facsimile transmission for many
    years to send wire photos between distant locations.
                 i)     Analogue Facsimile
                 ii)    Digital Facsimile
Q18 : What do you know about the steps of programming, explain in details??
    The process of production set of instructions to make computer do a job is called
    programming. Steps of programming are given below.
                 1.     Problem Definition
                 2.     Program Design
                 3.     Program Coding
                 4.     Program Testing(Debugging)
                 5.     Program Compilation
                 6.     Program Documentation.

    i)           Problem Definition
    This is the first step of programming in which problem is defined clearly. In this
    step objective of program, user of program, input and output requirements of
    programs are considered.

    ii)          Program Design
    This is the second step of programming. In this stage a computer steps by steps
    logical plan is paper. This logical plan is called algorithm. Algorithm describes by

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iii)         Program Coding.
iv)          The process of writing step of algorithm in computer understandable
instruction is called Coding. There are several programming languages available
to write programs like G.W Basic, Visual BASIC, Pascal, C++ etc.

v)           Program Testing(Debugging)
Testing is the process of making sure that program is error free and producing
required results. Program errors are called bugs and elimination bugs is called
debugging. There are following two types of error in a program.
       i)           Syntax Error
Syntax error occurs from the violation of program language rules. For example,
incorrect punctuation, undefined variables or misuse of variables.
       ii)   Logical Error
 Logical error is an error in planning the program logic. Computer cannot detect a
 logical error Bata version (Testing Version) of program is released and users are
 required to inform logical error.
vi)          Program Compilation
The conversion of source program into object program is called compilation. This
is the 5th step of programming. After debugging source program is compiled with
the help of compiler language. Compiler translates source program into object
program and machine code.
vii)         Program Documentation
This is the last step of programming in which a document is all step of program
described. Documentation (Manual) helps in error searching and modifying.

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Q19) Write a note on flowchart?
    A flowchart is a diagrammatic representation of the logic path of computer
    program. Flowchart is a way of assisting the programmer to layout logical steps
    of a program. It describes how the data is entered, how it is process and how
    result report is obtained and also the sequence of operations and decisions.
    For example a program of mark sheet of 20 students of a class is to be prepared.
    Each student appears in five subjects the required output is total obtained mark
    percentage and result.
Q20) Write down the rules and advantages of flowchart?
              Some important rules of flow chart are given below.
         i. First chalk out the logic then step into the details
         ii. Maintain uniform details for a required flow chart.
        iii. Use common words and statements.
        iv. Use uniform names and variables.
        v. Go from left to right and top to bottom.
        vi.      Break long flow chart and like them with appropriate labeled
    Some of the most important advantages of flow chart are give blow.
         1             It is easy for a programmer to explain the logic of program
         through flow chart.
         2             It can also serve as system model for the analyses.
         3             It provides a valuable documentation support.
         4             It makes coding easy.
         5             It can help in debugging.

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Q21 what is a file?
    A file is a collection of logically related records. Example for employee’s data
    base file is a collection of all employs records.
    For example, employee’s data bas file is a collection of all employees’ record.

    Q22 What is a key field?
    Ans A key field in a record is a unique data item which is used for identifying
    the records for accessing and processing purpose. The value of key field must b
    For example. Roll numbers in students records file and employ code number in
    employee record file.

Q23 Write down the types of file?
    The common types of files are given below.
    (1)      MASTR FILE
    A master is a file that consist all the necessary data of the activities of an
    organization. There can be a number of master files each for on activity such as
    a master file for pay roll a master file for stock etc. There are two types of master
             i)    Reference Master File
             ii)   Dynamic Master File

            i)     REFERENCE MASTER FILE
    A reference master file consists of relatively static record in which changes do
    not take place frequently. For example, a master file for items in a shop
    containing records consists of code item names and price.

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                 ii)     DYNAMIC MASTER FIL
            A dynamic master file consists of records in which changes takes place
            frequently. For example, the airline reservation file which gives details of
            passenger names, seats booked etc.

                 (2)     TRANSACTION FILE
            A transaction file is a file which is required in batch processing updating method.
            It accumulates active records that will be used update master file.

            Q24 Writ a not on file organization methods and access mode?
            Ans File Organization:
            The arrangement of records in a file is called file organization. The main
            objectives of file organization are given below.
(1)                      To provide an efficient method to locate records for processing.
(2)                      To facilitate file creation and maintenance in future.
            There are four common file organizations.

      (1)              SERIAL FILE
            A serial file is a file in which records are placed one after another physically
            adjacent to each other. There is no specific order in the arrangement of records.
            In magnetic tape records are written along the length of tape is serial file while on
            disk records are written along the tracks one by one. Serial files are usually
            created as temporary files. The serial file can be sorted. The main advantage of
            serial file is that the space on storage medium is utilized in the maximum.
                        Roll Name        Course Fee            Roll   Name        Course Fee
                        No                                     No

            Prepared by Inqilab Patel                    Typed by Shoaib Anwer Qambrani
      RIC- Ruknuddin Institute of Computer (Management &IT)                          IT for DBA-1      22

                       101    Shoaib     Cit         500     102        Anwer    Excel          700
                       RECORD NO 1                           RECORD NO 2

(2)                  SEQUNTIAL FILE
      A file which records are written in specific order is called sequential file. In
      sequential file records are written in a sequence, for example ordered by “Roll
      No” by “Bill No” by “Date” etc. a sequential file may be or may not be a serial file.
                       10    Qambra Word            500     104     Abdulla      Graphic       500
                       3     ni                                     h            s
                       RECORD NO 1                          RECORD NO 2

                        ADVANTAGES OF SEQUENTIAL FILE
               i.    Some         advantages   of     sequential   files   are       given          below
                     File design is simple.
              ii.    Locations of records require only the record key.
              iii.   Low cost file storage medium such as tape.
        i.       Sequential files are not suited for on line inquiry.
       ii.       Information on the file is not always current.
       iii.      Addition and deletion of records are not simple
      iv.        A new master file is always separately created as a result of sequential

      A file organization in which each record has its own address to make it directly
      accesses able is called “Direct Random Access File”. Random access file
      provides a way of accessing record directly. Records need not to be in any
      sequenced or physically adjacent. Random access file are created only on

      Prepared by Inqilab Patel                            Typed by Shoaib Anwer Qambrani
RIC- Ruknuddin Institute of Computer (Management &IT)                 IT for DBA-1   23

diskettes. The record can be edited and deleted easily. Random access files are
best suited for online processing system where current information is required.
Some common advantages of direct random access file are given below.
  i.     Direct access of records is possible.
 ii.     Up to the minute information is available on the file.
 iii.    File can be simultaneously updated.
iv.      Addition and master file is created for updating a random access file.
Some disadvantages of direct random access file are given below.
  i.     Less efficient use of storage space.
 ii.     Not well suited for batch processing.
 iii.    More expensive medium.
iv.      Data security is less.
An index sequential file is a sequential file organized serially on key field and in it
an index is maintained to access records. The index of file is like an index of
book. The file is divided into a number of blocks and the height in each block is
             KEY                              STARTING        ADDRESS
                                              OF BLOCK
             125                              12
             86                               19
             1420                             24
             1600                             42
             1829                             49

Prepared by Inqilab Patel                        Typed by Shoaib Anwer Qambrani
      RIC- Ruknuddin Institute of Computer (Management &IT)             IT for DBA-1   24

      All the records which index value 125 are in the first block on storage medium
      which starts at the address 12 on the disk and so on. It’s a record width key 1236
      is required it will be in the 3rd block starting at address 24 with this block the
      record is searched sequentially.
i.       This is a faster method of searching.
ii.      It is suitable for both sequential and online processing.
i.       Less efficient use of storage space.
ii.      Addition and deletion are more complex.

      Prepared by Inqilab Patel                    Typed by Shoaib Anwer Qambrani

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