Thursday, 28 June 2012

Bill Gates Interview


The Bill Gates Interview

A candid conversation with the sultan of software about outsmarting his rivals

"The Wallet PC is a futuristic device. Instead of having tickets to the theater, your Wallet PC will digitally prove that you paid. It's our vision of the small, portable PC of, say, five years from now."
"If we weren't still hiring great people and pushing ahead, it would be easy to fall behind and become a mediocre company. Fear should guide you, but it should be latent. I consider failure on a regular basis."

"We bet the company on Windows and we deserve to benefit. It was a risk that's paid off immensely. In retrospect, committing to the graphics interface seems so obvious that now it's hard to keep a straight face."



A youngish man who looks like a graduate student sits on the door of his unpretentious dormlike room, spooning Thai noodles from a plastic container. His glasses are smudged, his clothes are wrinkled, his hair is tousled like a boy's. But, when he talks, people listen. Certainly no person on the campus can talk about the future, as he does, with the riveting authority of someone who not only knows what's in store for tomorrow but is a major force in shaping that future as well.
Yet this is an office, not a dorm room. And, while everyone calls the complex of 25 buildings a campus, it's not a college or university. It's the sprawling Microsoft headquarters in Redmond, Washington. And the speaker is no grad student. He's William H. Gates III, chief executive and co-founder of the largest software company in the world, which made $953 million last year on sales of $3.75 billion. As Microsoft's largest stockholder, he's worth nearly $6.1 billion, making him this country's second wealthiest man and, at 38, its youngest self-made billionaire. (Gates pal, investor Warren Buffett, is first, though they occasionally trade places depending on stock prices.)
Microsoft's wealth and power just grow and grow, asserts Fortune magazine. CEO Bill Gates could buy out an entire years production of his 99 nearest competitors, burn it, and still be worth more than Rupert Murdoch or Ted Turner. Microsoft's $25 billion market value tops that of Ford, General Motors, 3M, Boeing, RJR Nabisco, General Mills, Anheuser-Busch or Eastman Kodak.
With size comes power. Microsoft dominates the PC market with its MS-DOS operating system, the basic software that lets the computer understand your commands and carry them out. MS-DOS runs on 90 percent of the worlds IBM and IBM-clone computers. Microsoft has extended that presence with Windows, a graphics interface environment that runs on top of MS-DOS and will, according to Gates, replace DOS in future versions. Microsoft also supplies about 50 percent of the worlds software applications: programs such as Excel (spreadsheets), Microsoft Word (word processing) and Access (data bases). It is also in the business of networking. And multimedia. And CD-ROMs. And books. And as an early supporter of the Macintosh computer, Microsoft virtually owns the Mac application market.
The future looks equally promising. Gates recently announced that Microsoft and McCaw Cellular Communications will form a joint 840-satellite global communications network. At the same time, Gates also acknowledged that he was in high-level negotiations with AT&T about a series of ventures that could include interactive television, on-line computer services and software. This is in addition to a previously announced joint venture with Nippon Telegraph and Telephone, the worlds second-largest phone company, and with cable giant John Malone and his Tele-Communications, Inc. aimed at launching a digital cable TV network for computer users. Viewers would be able to interact with programs, download software and shop for products and services. Other partnerships loom as well, including ones with publishing companies and Hollywood studios.

Rejection In an Interview


Major Reasons For Rejection In an Interview




                  There is always some or the other reason behind failures in an interview!! In order to succeed, 
it is very essential to remove all your weaknesses as soon as you come across them. Explore a 
few common reasons for rejection of individuals in the interview through this article!!
Not taking the interview seriously. Don’t make the mistake of thinking the interview is just a 
formality. Even if all the preliminaries have gone well, don’t be cavalier and start imagining how 
you’ll start spending your new salary. The biggest error you can make is to assume that, 
because you’ve gotten this far, the job is in.
Poor attitude. Many candidates come across as arrogant. While employers can afford to be 
self-centered, candidates cannot.

Interview Preparation





Interview Preparation




STEP I:------
    There is no better way of beginning the interview process than with a warm greeting to the 
panelists. A cheery greeting coupled with a sunny disposition is a very effective ice-breaker.
Face the panel, but don’t fall of the chair in a headlong rush-and-skid attempt to tell your story. 
Take one step at a time. If you place your foot on slippery ground, you could be ejecting out on a 
free fall. So prepare, fortify your thoughts, re-jig your memory, and script and design your story 
(without frills and falsity). Without the right preparation and storyboard, you could be a loser at 
the interview.
Here are a few preparation tips that books on interviews sometimes overlook.
Before the interview:
1. Chronological Outline of Career and Education Divide your life into “segments” defining 
your university, first job, second job. For each stage, jot down :

How to face Interview


  How to face HR Interview


         For your first few interviews your background is important - your school, the medium and the place you 
studied in, all serve to give the interviewer an idea about you. Carry a copy of the bio-data that you have 
already sent, and the interview letter. Keep the extra copy with you, just in case. Show the interview 
letter to the receptionist/interviewer to establish your credentials, but keep this letter with you. This 
gives you, for your future reference, a time and date record of your interview, gives the official address 
of the 
company for further correspondence and clarifications, and may give you the name and designation of 
the person you are to report to.

Interview Questions


Fifty Standard Entry Level Interview Questions


Think before answering all these questions. The questions are very simple but difficult to answer 
because there is no CORRECT answer.
1. Tell me about yourself.
2. What do you want to do with your life?
3. Do you have any actual work experience?
4. How would you describe your ideal job?
5. Why did you choose this career?
6. When did you decide on this career?
7. What goals do you have in your career?

Body language


 Here are common body language cues to watch out for in an interview:


1. A firm handshake 
A recruiter's first impression of you is often formed when you shake hands. A firm handshake will give 
the right impression. But not too firm - that can seem arrogant or too challenging. 
2. Arms folded across the chest 
You may feel comfortable sitting that way, but studies show that the interviewer will read this as 
defensive. 
3. Leaning forward 
This means you have an intense interest in what the interviewer is saying or vice versa. 
4. Head tilted to the side 

Confidence to Get Success


Confidence Means:


         Every day is a new day in our life. There is much to do today. The early morning sun inspires us to start 
things freshly and put back our past. Only a handful of us make use of this fresh bunch of energy. In 
various walks of life this affects the way we behave and our confidence level. Confidence is a key to 
survive in this world. It is the only key tool to win the rat race in every walk of life. Confidence in ones 
owns capabilities combined with sincere efforts help one to achieve unthinkable heights. But many 
times we see that this basic element of confidence is missing in us. 

Monday, 25 June 2012

brief introduction about Satyam


Satyam Computer Services Ltd is one of the leading global consulting and IT services company that offers end-to-end IT solutions for a range of key verticals and horizontals. Satyam Computers has domain expertise in verticals such as Automotive, Banking & Financial Service, Insurance & Healthcare, Manufacturing, Telecom, Infrastructure, Media, Entertainment, and Semiconductors.

Satyam has nearly 40,000 employees on its rolls,

Popular interview questions and answers


Interview Q and A

  1. Describe a challenging work issue you had to face, and how you dealt with it? Consider what would be the requirements of the ‘new’ job/organization and find something in your past that highlights a skill, experience or situation that might occur or be needed going forward. It is always a good idea to make lists in preparation for interviews: New job will need I can provide Proof/example For your proofs, list (for yourself) examples of when you used the skill, exhibited the characteristic or handled the problem. This will not only give you ’short stories’ to relate in an interview, it will also bolster your confidence and target your job search.
  2. If you were on a merry-go-round, what song would be playing? If you were going to be an animal on the merry-go-round, what would you be?”

brief introduction about Google


Google

From Wikipedia, the free encyclopedia

Jump to: navigation, search
This article is about the corporation. For the search engine, see Google search. For other uses, see Google (disambiguation).
Google Inc.
Founded
Headquarters
Key people
Eric E. Schmidt, CEO/Director
Sergey Brin, Co-Founder, Technology President
Larry Page, Co-Founder, Products President
George Reyes, CFO

C,C++ Questions


C,C++ Questions




1. Base class has some virtual method and derived class has a method with the same name. If we initialize the base class pointer with derived
object,. calling of that virtual method will result in which method being called? 

a. Base method
b. Derived method..

Ans. b
2. For the following C program
#define AREA(x)(3.14*x*x)
main()
{float r1=6.25,r2=2.5,a;
a=AREA(r1);
printf("\n Area of the circle is %f", a);
a=AREA(r2);
printf("\n Area of the circle is %f", a);
}

What is the output?

Interview TIP


Interview Tips: “Walk me through your resume”

by JunLoayza |
Using the FD Edge Resume Optimization Strategy, this question is straightforward. Talk about each section of your resume in a linear, clear, enthusiastic way. Do not go overly in-depth into any one item, but do not remain too superficial either. Touch on your academic, professional, leadership, technical, and personal qualifications, concluding with a statement about why these experiences are important for your industry.

keyboard Shortcuts



Press
To
CTRL+C
Copy.
CTRL+X
Cut.
CTRL+V
Paste.

Data Structures interview Questions


Data Structures

                                    HCL
1.What data structes you will use if you want to go to first record from
the last and vice versa?
ans.: doubly linked circular list

2.  given a height balanced tree. If we add one more node , how
    many nodes gets unbalanced ? Ans. 3

3. Given a arbitrary pointer  to an element in a singly linked list?
    what is the time complexity for its deletion . 

MS-Office Tutorial


Ms – WORD

FILE MENU: -
New: -
In word to create a file first we have to select the file option from menu bar.  By selecting New it displays the new dialog box.  In that select type of doc you want to create (letter, menu, . . .. etc.,). And finally click on OK button.

Open: -
            By clicking this option we can open already existing file.

Complete JavaScript Meterial


JAVA SCRIPT

What is JavaScript ?

JavaScript is a scripting language produced by Netscape for use within HTML Web pages.      
JavaScript started life as LiveScript, but Netscape changed the name, possibly because of the excitement being generated by Java.to JavaScript. JavaScript made its first appearance in Netscape 2.0 in 1995 with a name LiveScript.
JavaScript is a lightweight, interpreted programming language with object-oriented capabilities that allows you to build interactivity into otherwise static HTML pages.
The general-purpose core of the language has been embedded in Netscape, Internet Explorer, and other web browsers
  • JavaScript was designed to add interactivity to HTML pages
  • JavaScript is a scripting language
  • A scripting language is a lightweight programming language
  • JavaScript is usually embedded directly into HTML pages
  • JavaScript is an interpreted language (means that scripts execute without preliminary compilation)

Are Java and JavaScript the Same?

NO!

Thursday, 21 June 2012

Aptitude Questions ans solutions


Aptitude Questions


1.If 2x-y=4 then 6x-3y=?
(a)15
(b)12
(c)18
(d)10


Ans. (b)
2.If x=y=2z and xyz=256 then what is the value of x?

Aptitude Questions With Solutions


Aptitude Questions


Solve the following and check with the answers given at the end.


1. It was calculated that 75 men could complete a piece of work in 20 days. When work was scheduled to commence, it was found necessary to send 25 men to another project. How much longer will it take to complete the work?


2. A student divided a number by 2/3 when he required to multiply by 3/2. Calculate the percentage of error in his result.


3. A dishonest shopkeeper professes to sell pulses at the cost price, but he uses a false weight of 950gm. for a kg. His gain is …%.


4. A software engineer has the capability of thinking 100 lines of code in five minutes and can type 100 lines of code in 10 minutes. He takes a break for five minutes after every ten minutes. How many lines of codes will he complete typing after an hour?

Wednesday, 20 June 2012

HR Interview Tips


HR Interviews

HR Interviews can be a source of stress and anxiety when you are looking for a job. So much can be riding on the success of the interview that an individual may become overwhelmed by the interviewing process itself, causing the individual to represent in a less-than flattering light. The HR Interview articles in this section of tutorials will assist you in preparing for one of the important interview process.
HR interview is your chance to make a good impression on your potential employer and ultimately, get the job. How you present yourself, what you wear, how you answer difficult questions and your general attitude all play key roles in HR interviews. Being prepared is the best way to gain employment in today’s competitive job market. Knowing relevant information about the company you are interviewing for, knowledge of the job and the industry surrounding the job can make or break an interview.
All interviews are not the same and HR interviews are often times a screening process that can earn you a follow-up or selection interview within the company. If an individual passes the selection interview, he may be required to participate in a group interview for final analysis. The key to success in HR interviews is to be yourself while respecting your employer.

Group Discussions


Group Discussions

As a professional in the working world, there will be times when you will be required to participate in group discussions. This section offers helpful articles analyzing the rules for success in group discussions. Your career and status within your field can improve if you learn some guidelines and tactics that refine your group discussion skills.
If you have trouble speaking out of turn, interrupting others or a lack of confidence about properly expressing yourself, the techniques about handling yourself in a group discussion can be invaluable. This is helpful advice for any individual working with other people in any industry. Discussing ideas in a group is one of the best ways to solve the problem. When a person becomes a burden in group discussions due to lack of experience, an excess amount of excitement or a general lack of social skills, these factors can contribute to how you are viewed by your colleagues and superiors in the workplace.
If you are in a managerial position, it is imperative to provide an open forum for discussion where your subordinates feel comfortable sharing their ideas. If a person participating in a group discussion feels that their opinion will be ignored then the members within the group will hesitate to share what could be valuable solutions to business issues in group discussions.
Training Index
  1. How to Prepare for Group Discussions

    How To Prepare For Group Discussions If you are participating in a group discussion it is important to make sure you re prepared before the discussion begins. While small groups may not be good for the distribution of information group discussions are excellent for situations where members need to learn concepts or solve problems. To obtain a

Time Management


Time Management


                  Time management consists of tools and activities that help an individual effectively manage and strategize his time. This is a very important concept for everyone to attempt to learn and master over the course of his career. Through effective time management, one can increase individual or group productivity and experience larger profits that will lead to a more satisfying overall work and life experience.

Web Services

Web Services Introduction


Generate advanced XSLT stylesheets, web pages and reports using intuitive drag-and-drop functionality, intelligent entry-helpers, and more. See how easy it is to work with XSLT in this tool from the makers of XMLSpy. Features include:
  • Visual drag & drop stylesheet design
  • Auto-generation of XSLT 1.0/2.0 and XSL:FO
  • Advanced report design based on XML, XBRL and database sources
  • Support for HTML5, CSS3, and JavaScript
  • True electronic form design through absolute positioning in design templates
  • Advanced functions for dynamic presentation
  • Ability to import existing and external XSLT files
  • Charts, graphs, bar codes, and more
  • 32 bit & 64 bit versions
  • And much more!
 Web Services can convert your applications into Web-applications.
Web Services are published, found, and used through the Web.

 What You Should Already Know

Tuesday, 19 June 2012

Java1.5 Installation Steps

Java1.5 Installation Steps.

Double click the given software.
Accept the terms of license agreement and press NEXT.
The software first will ask for installing the SDK press NEXT again. This will take few minutes to install.
Then the software will ask for installing JRE press NEXT to continue.
Select the browser you want to register with java to plug-in and click NEXT.
Click on Finish button to complete your installation.

Sunday, 17 June 2012

NetWorking interview Q


Network:


1.In OSI, terminal emulation is done in (HCL)
a)semion b)appl.. c)presenta... d)transport
ans: b


2)Which are the different network toplogies ?


3) Tell an example of bus type network.
ethernet.


4)What is the Bandwidth of ethernet ?


5)Explain the advantage and disadvantage of ethernet ?


6)Which is the protocol used in ethernet. (CSMA/CD)
bridges, routers and generators


7)What is the advantage of Ring network ?
Compare it with ethernet.


8) Piggy backing is a technique for
a) Flow control b) sequence  c) Acknowledgement   d) retransmition
ans:   c    piggy backing
hughes


9      16 bit mantissa and 8 bit exponent can present what maximum value?
4bit window size in sliding window protocol, how many acknowledements can be held?
CSMA/Cd protocol used in
Ans

Design Patterns Interview Questions


Design Patterns Interview Questions




1) What is a software design pattern?
A design pattern is a solution to a general software problem within a particular context.
• Context : A recurring set of situations where the pattern applies.
• Problem : A system of forces (goals and constraints) that occur repeatedly in this
context.
• Solution : A description of communicating objects and classes (collaboration) that
can be applied to resolve those forces.
Design patterns capture solutions that have evolved over time as developers strive for
greater flexibility in their software. Whereas class libraries are reusable source code, and
components are reusable packaged objects, patterns are generic, reusable design
descriptions that are customized to solve a specific problem. The study of design patterns
provides a common vocabulary for communication and documentation, and it provides a
framework for evolution and improvement of existing patterns.

Group Discussion Tips


Group Discussion


Many companies conduct group discussion after the written test so as to check on your interactive skills and how good you are at communicating with other people. The GD is to check how you behave, participate and contibute in a group, how much importance do you give to the group objective as well as your own, how well do you listen to viewpoints of others and how open-minded are you in accepting views contrary to your own. The aspects which make up a GD are verbal communication, non-verbal behaviour, conformation to norms, decision-making ability and cooperation. You should try to be as true as possible to these aspects.
General Tips

C language Interview Questions

C language FAQ


1. The C language terminator is 
(a) semicolon
(b) colon
(c) period
(d) exclamation mark


2. What is false about the following -- A compound statement is 
(a) A set of simple statments
(b) Demarcated on either side by curly brackets
(c) Can be used in place of simple statement
(d) A C function is not a compound statement.

Sunday, 10 June 2012

InterView Skill Tips



Interview Questions


BEHAVIORAL INTERVIEW

More employers are using behavioral interviewing in the hiring process. This type of interview is based on the idea that the best way to predict your future performance is to examine your past and present performance in a similar situation. It focuses on experiences, behaviors, knowledge, skills and abilities that are job related.

With the Behavioral interview Employers predetermine which skills are necessary for the job for which they are looking and then ask very pointed questions to determine if the candidate possesses those skills. Currently, 30 percent of all organizations are using behavioral interviewing to some degree. Prepare for Behavioral Interviews by researching what job competencies an employer might seek.
Why should you prepare for behavioral interview?




TCS registration link

Saturday, 9 June 2012

Walk-ins links

C,C++ /Testing Developers (Freshers) at Conflux Software 
Software Engineer (Freshers & Exp) at Sandisk India 
Hiring Software Engineer 4.5L - 5.5L P.A (Freshers) at TIBCO
SAP PM Consultant (Freshers & Exp) at Capgemini 
Software Engineer Trainee (Freshers & Exp) at Nr Switch N Radio Services 
Recruiting Software Engineer (Freshers & Exp) at Solutions Infini
Management Trainees (Freshers) at Coal India Limited (CIL)
Recuitiment Notification at Indian Air Force 2012
TCS Registration Link for 2012 Freshers
Trainee Software Engineer (Freshers & Exp) at Kilmist InfoTech 

Friday, 8 June 2012

Julaayi Telugu Mp3 Songs


Julaayi  Mp3 Promo Songshttp://4.bp.blogspot.com/-QgMHUnfU9yE/T5U4gfY0n1I/AAAAAAAAKNo/l8dYqPyI0-U/s1600/AlluArjun_Julayi_Wallpaper_.jpg

Julayi (2012) Original ACD RIP VBR [320Kbps]
 Cast : Allu Arjun, Iliyana
Banner : Haarika & Hassine Creations
Producer : S.Radha Krishna
Director : Trivikram
Music Director : Devi Sri Prasad
 Full Songs Are Not Released Yet Now...
Please Bookmark this page to get Songs First On Net..
As Soon As Songs Released i will post the songs in this same page

Promo Songs Are Released With 1 Min Duration..
TrackList

Pakado Pakado Song
Singers: Malgadi Subha, Devi Sri Prasad

Osey Osey Song
Singers: Jessi Gift

O Madhu Song
Singer: Adnan Sami

Mee intiki Mundhu Song
Singers:Sagar And Ranina Reddy

Julai Song
Singers: Suchith Sureshan, Priya Hemesh

Chakkani Bike Undi Song
Singers: Tippu , Megha

Download All Songs In Single File
Download Link : Mediafire

Seethamma Vakitlo Sirimalle Chettu

Seethamma Vakitlo Sirimalle Chettu Mp3 Songs Free Download

Seethamma Vakitlo Sirimalle Chettu (2012) Telugu Mp3 Songs Free Download
Cast : Vicktory Venkatesh, Prince Mahesh Babu, Samantha, Anjali
Directed : Srikanth Addala
Producer : Dil Raju
Music : Mickey J Meyar
Exclusive Song of Seethamma Vakitlo Sirimalle Chettu Extended Version

Track List

Seethamma Vakitlo Sirimalle Chettu (Theme Song)
Download Link : MediaFire

Wednesday, 6 June 2012

Walk-ins

Software Engineer (Freshers & Exp) at Xchanging Technology 
Job Fair 2012 ( 2,500+ Vacancies From 40+ Leading Corporates ) 
Software Developer (Freshers & Exp) at QMM Technologies Pvt Ltd 
Operations Executive (Freshers & Exp) at iNautix Technologies 
Web Developers (Freshers) at Nispaara Solutions India Pvt.Ltd 
Walk-in for Software Test Engineers (Freshers & Exp) at Nidhi Technologies
Junior Software Engineer 3.5L - 5L P.A (Freshers) at Alacriti Infosystems
Software Engineer (Freshers & Exp) at iGrapix Solutions
Desktop Administrator (Freshers & Exp) at Optit Technologies
Openings for Trainee Technician/ Company Trainee at HMT Machine Tools Limited
Right Angle Solution Hiring Software Developers (Freshers)
Software Support Executive (Freshers & Exp) at i2e Technologies
VC++ Developer (Freshers) at Bhasinsoft India Ltd
Recruiting Software Developer (Freshers) at SSDN Technologies







share the information

Monday, 4 June 2012

Data Base interview Questions


RDBMS Concepts

1.      What is database?
A database is a logically coherent collection of data with some inherent meaning, representing some aspect of real world and which is designed, built and populated with data for a specific purpose.

2.      What is DBMS?
It is a collection of programs that enables user to create and maintain a database. In other words it is general-purpose software that provides the users with the processes of defining, constructing and manipulating the database for various applications.

3.      What is a Database system?
The database and DBMS software together is called as Database system.

4.      Advantages of DBMS?
Ø  Redundancy is controlled.
Ø  Unauthorised access is restricted.
Ø  Providing multiple user interfaces.
Ø  Enforcing integrity constraints.
Ø  Providing backup and recovery.

5.      Disadvantage in File Processing System?
Ø  Data redundancy & inconsistency.
Ø  Difficult in accessing data.
Ø  Data isolation.
Ø  Data integrity.
Ø  Concurrent access is not possible.
Ø  Security Problems.

6.      Describe the three levels of data abstraction?
The are three levels of abstraction:
Ø  Physical level: The lowest level of abstraction describes how data are stored.
Ø  Logical level: The next higher level of abstraction, describes what data are stored in database and what relationship among those data. 
Ø  View level: The highest level of abstraction describes only part of entire database.
7.      Define the "integrity rules"
There are two Integrity rules.
Ø  Entity Integrity: States that “Primary key cannot have NULL value”
Ø  Referential Integrity: States that “Foreign Key can be either a NULL value or should be Primary Key value of other relation.

8.      What is extension and intension?
Extension -
It is the number of tuples present in a table at any instance. This is time dependent.
Intension -
It is a constant value that gives the name, structure of table and the constraints laid on it.

9.      What is System R? What are its two major subsystems?
System R was designed and developed over a period of 1974-79 at IBM San Jose Research Center. It is a prototype and its purpose was to demonstrate that it is possible to build a Relational System that can be used in a real life environment to solve real life problems, with performance at least comparable to that of existing system.
Its two subsystems are
Ø  Research Storage
Ø  System Relational Data System.

10.  How is the data structure of System R different from the relational structure?
Unlike Relational systems in System R
Ø  Domains are not supported
Ø  Enforcement of candidate key uniqueness is optional
Ø  Enforcement of entity integrity is optional
Ø  Referential integrity is not enforced

11.  What is Data Independence?
            Data independence means that “the application is independent of the storage structure and access strategy of data”. In other words, The ability to modify the schema definition in one level should not affect the schema definition in the next higher level.
Two types of Data Independence:
Ø  Physical Data Independence: Modification in physical level should not affect the logical level.   
Ø  Logical Data Independence: Modification in logical level should affect the view level.    
     NOTE:  Logical Data Independence is more difficult to achieve

12.  What is a view? How it is related to data independence?
A view may be thought of as a virtual table, that is, a table that does not really exist in its own right but is instead derived from one or more underlying base table. In other words, there is no stored file that direct represents the view instead a definition of view is stored in data dictionary.
Growth and restructuring of base tables is not reflected in views. Thus the view can insulate users from the effects of restructuring and growth in the database. Hence accounts for logical data independence.

13.  What is Data Model?
 A collection of conceptual tools for describing data, data relationships data semantics and constraints.

14.  What is E-R model?
This data model is based on real world that consists of basic objects called entities and of relationship among these objects. Entities are described in a database by a set of attributes.

15.  What is Object Oriented model?
This model is based on collection of objects. An object contains values stored in instance variables with in the             object. An object also contains bodies of code that operate on the object. These bodies of code are called methods. Objects that contain same types of values and the same methods are grouped together into classes.

16.  What is an Entity?
It is a 'thing' in the real world with an independent existence.

17.  What is an Entity type?
It is a collection (set) of entities that have same attributes.

18.  What is an Entity set?
It is a collection of all entities of particular entity type in the database.

19.  What is an Extension of entity type?
The collections of entities of a particular entity type are grouped together into an entity set.

20.  What is Weak Entity set?
An entity set may not have sufficient attributes to form a primary key, and its primary key compromises of its partial key and primary key of its parent entity, then it is said to be Weak Entity set.

21.  What is an attribute?
It is a particular property, which describes the entity.

22.  What is a Relation Schema and a Relation?
A relation Schema denoted by R(A1, A2, …, An) is made up of the relation name R and the list of attributes Ai that it contains. A relation is defined as a set of tuples. Let r be the relation which contains set tuples (t1, t2, t3, ..., tn). Each tuple is an ordered list of n-values t=(v1,v2, ..., vn).

23.  What is degree of a Relation?
It is the number of attribute of its relation schema.

24.  What is Relationship?
It is an association among two or more entities.

25.  What is Relationship set?
The collection (or set) of similar relationships.

26.  What is Relationship type?  
Relationship type defines a set of associations or a relationship set  among a given set of entity types.  

27.  What is degree of Relationship type?
It is the number of entity type participating.

25.  What is DDL (Data Definition Language)?
A data base schema is specifies by a set of definitions expressed by a special language called DDL.

26.  What is VDL (View Definition Language)?
It specifies user views and their mappings to the conceptual schema.

27.  What is SDL (Storage Definition Language)?
This language is to specify the internal schema. This language may specify the mapping between two schemas.

28.  What is Data Storage - Definition Language?
The storage structures and access methods used by database system are specified by a set of definition in a special type of DDL called data storage-definition language.

29.  What is DML (Data Manipulation Language)?
This language that enable user to access or manipulate data as organised by appropriate data model.
Ø  Procedural DML or Low level: DML requires a user to specify what data are needed and how to get those data.
Ø  Non-Procedural DML or High level:  DML requires a user to specify what data are needed without specifying how to get those data.

31.  What is DML Compiler?
It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand.

32.  What is Query evaluation engine?
It executes low-level instruction generated by compiler.

33.  What is DDL Interpreter?
It interprets DDL statements and record them in tables containing metadata.

34.  What is Record-at-a-time?
The Low level or Procedural DML can specify and retrieve each record from a set of records. This retrieve of a record is said to be Record-at-a-time.

35.  What is Set-at-a-time or Set-oriented?
The High level or Non-procedural DML can specify and retrieve many records in a single DML statement. This retrieve of a record is said to be Set-at-a-time or Set-oriented.

36.  What is Relational Algebra?
It is procedural query language. It consists of a set of operations that take one or two relations as input and produce a new relation.

37.  What is Relational Calculus?
It is an applied predicate calculus specifically tailored for relational databases proposed by E.F. Codd. E.g. of languages based on it are DSL ALPHA, QUEL.

38.  How does Tuple-oriented relational calculus differ from domain-oriented relational calculus
The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL
The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE.

39.  What is normalization?
It is a process of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to achieve the properties
Ø  Minimizing redundancy
Ø  Minimizing insertion, deletion and update anomalies.  

40.  What is Functional Dependency?  
A Functional dependency is denoted by X     Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component Y.

41.  When is a functional dependency F said to be minimal?
Ø  Every dependency in F has a single attribute for its right hand side.
Ø  We cannot replace any dependency X    A in F with a dependency Y   A where Y is a proper subset of X and still have a set of dependency that is equivalent to F.
Ø  We cannot remove any dependency from F and still have set of dependency that is equivalent to F.

42.  What is Multivalued dependency?
Multivalued dependency denoted by X        Y specified on relation schema R, where X and Y are both subsets of R, specifies the following constraint on any relation r of R: if two tuples t1 and t2 exist in r such that t1[X] = t2[X] then t3 and t4 should also exist in r with the following properties
Ø  t3[x] = t4[X] = t1[X] = t2[X]
Ø  t3[Y] = t1[Y] and t4[Y] = t2[Y]
Ø  t3[Z] = t2[Z] and t4[Z] = t1[Z] 
where [Z = (R-(X U Y)) ]
             
43.  What is Lossless join property?
It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition.

44.  What is 1 NF (Normal Form)?
The domain of attribute must include only atomic (simple, indivisible) values.

45.  What is Fully Functional dependency?
It is based on concept of full functional dependency. A functional dependency     X    Y is full functional dependency if removal of any attribute A from X means that the dependency does not hold any more.

46.  What is 2NF?
A relation schema R is in 2NF if it is in 1NF and every non-prime attribute A in R is fully functionally dependent on primary key.

47.  What is 3NF?
A relation schema R is in 3NF if it is in 2NF and for every FD X    A either of the following is true
Ø  X is a Super-key of R.
Ø  A is a prime attribute of R.
In other words, if every non prime attribute is non-transitively dependent on primary key.

48.  What is BCNF (Boyce-Codd Normal Form)?
            A relation schema R is in BCNF if it is in 3NF and satisfies an additional constraint that for every FD X     A, X must be a candidate key.
      
49.  What is 4NF?
A relation schema R is said to be in 4NF if for every Multivalued dependency         X         Y that holds over R, one of following is true
Ø  X is subset or equal to (or) XY = R.
Ø  X is a super key.

50.  What is 5NF?
A Relation schema R is said to be 5NF if for every join dependency  {R1, R2, ..., Rn} that holds R, one the following is true
Ø  Ri = R for some i.
Ø  The join dependency is implied by the set of FD, over R in which the left side is key of R.  
51.  What is Domain-Key Normal Form?
A relation is said to be in DKNF if all constraints and dependencies that should hold on the the constraint can be enforced by simply enforcing the domain constraint and key constraint on the relation.

52.  What are partial, alternate,, artificial, compound and natural key?
Partial Key:
It is a set of attributes that can uniquely identify weak entities and that are related to same owner entity. It is sometime called as Discriminator.
Alternate Key:
            All Candidate Keys excluding the Primary Key are known as Alternate Keys.
Artificial Key:
 If no obvious key, either stand alone or compound is available, then the last resort is to simply create a key, by assigning a unique number to each record or occurrence. Then this is known as developing an artificial key.
            Compound Key:
                 If no single data element uniquely identifies occurrences within a construct, then combining multiple elements to create a unique identifier for the construct is known as creating a compound key.
            Natural Key:
            When one of the data elements stored within a construct is utilized as the primary key, then it is called the natural key.

53.  What is indexing and what are the different kinds of indexing?
Indexing is a technique for determining how quickly specific data can be found.
Types:
Ø  Binary search style indexing
Ø  B-Tree indexing
Ø  Inverted list indexing
Ø  Memory resident table
Ø  Table indexing

54.  What is system catalog or catalog relation? How is better known as?
A RDBMS maintains a description of all the data that it contains, information about every relation and index that it contains. This information is stored in a collection of relations maintained by the system called metadata. It is also called data dictionary.

55.  What is meant by query optimization?
The phase that identifies an efficient execution plan for evaluating a query that has the least estimated cost is referred to as query optimization.

56.  What is join dependency and inclusion dependency?
Join Dependency:
                        A Join dependency is generalization of Multivalued dependency.A JD {R1, R2, ..., Rn} is said to hold over a relation R if R1, R2, R3, ..., Rn is a lossless-join decomposition of R . There is no set of sound and complete inference rules for JD.
            Inclusion Dependency:
                        An Inclusion Dependency is a statement of the form that some columns of a relation are contained in other columns. A foreign key constraint is an example of inclusion dependency.

57.  What is durability in DBMS?
Once the DBMS informs the user that a transaction has successfully completed, its effects should persist even if the system crashes before all its changes are reflected on disk. This property is called durability.

58.  What do you mean by atomicity and aggregation?
Atomicity:
Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete transactions. DBMS ensures this by undoing the actions of incomplete transactions.
            Aggregation:
            A concept which is used to model a relationship between a collection of entities and relationships. It is used when we need to express a relationship among relationships.

59.  What is a Phantom Deadlock?
In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to identify deadlocks that do not really exist. Such situations are called phantom deadlocks and they lead to unnecessary aborts.

60.  What is a checkpoint and When does it occur?
A Checkpoint is like a snapshot of the DBMS state. By taking checkpoints, the DBMS can reduce the amount of work to be done during restart in the event of subsequent crashes.

61.  What are the different phases of transaction?
Different phases are
Ø  Analysis phase
Ø  Redo Phase
Ø  Undo phase

62.  What do you mean by flat file database?
It is a database in which there are no programs or user access languages. It has no cross-file capabilities but is user-friendly and provides user-interface management.

63.  What is "transparent DBMS"?
It is one, which keeps its Physical Structure hidden from user.

64.  Brief theory of Network, Hierarchical schemas and their properties
Network schema uses a graph data structure to organize records example for such a database management system is CTCG while a hierarchical schema uses a tree data structure example for such a system is IMS.

65.  What is a query?
            A query with respect to DBMS relates to user commands that are used to interact with a data base. The query language can be classified into data definition language and data manipulation language.

66.  What do you mean by Correlated subquery?
            Subqueries, or nested queries, are used to bring back a set of rows to be used by the parent query. Depending on how the subquery is written, it can be executed once for the parent query or it can be executed once for each row returned by the parent query. If the subquery is executed for each row of the parent, this is called a correlated subquery.
A correlated subquery can be easily identified if it contains any references to the parent subquery columns in its WHERE clause. Columns from the subquery cannot be referenced anywhere else in the parent query. The following example demonstrates a non-correlated subquery.
 E.g. Select * From CUST Where '10/03/1990' IN (Select ODATE From ORDER Where CUST.CNUM = ORDER.CNUM)

67.  What are the primitive operations common to all record management systems?
Addition, deletion and modification.

68.  Name the buffer in which all the commands that are typed in are stored
            ‘Edit’ Buffer

69.  What are the unary operations in Relational Algebra?
            PROJECTION and SELECTION.

70.  Are the resulting relations of PRODUCT and JOIN operation the same?
            No.
            PRODUCT: Concatenation of every row in one relation with every row in another.
            JOIN: Concatenation of rows from one relation and related rows from another.

71.  What is RDBMS KERNEL?
            Two important pieces of RDBMS architecture are the kernel, which is the software, and the data dictionary, which consists of the system-level data structures used by the kernel to manage the database
            You might think of an RDBMS as an operating system (or set of subsystems), designed specifically for controlling data access; its primary functions are storing, retrieving, and securing data. An RDBMS maintains its own list of authorized users and their associated privileges; manages memory caches and paging; controls locking for concurrent resource usage; dispatches and schedules user requests; and manages space usage within its table-space structures
.
72.  Name the sub-systems of a RDBMS
            I/O, Security, Language Processing, Process Control, Storage Management, Logging and Recovery, Distribution Control, Transaction Control, Memory Management, Lock Management

73.  Which part of the RDBMS takes care of the data dictionary? How
            Data dictionary is a set of tables and database objects that is stored in a special area of the database and maintained exclusively by the kernel.

74.  What is the job of the information stored in data-dictionary?
            The information in the data dictionary validates the existence of the objects, provides access to them, and maps the actual physical storage location.

75.  Not only RDBMS takes care of locating data it also
            determines an optimal access path to store or retrieve the data

76.  How do you communicate with an RDBMS?
            You communicate with an RDBMS using Structured Query Language (SQL)

77.  Define SQL and state the differences between SQL and other conventional programming Languages
SQL is a nonprocedural language that is designed specifically for data access operations on normalized relational database structures. The primary difference between SQL and other conventional programming languages is that SQL statements specify what data operations should be performed rather than how to perform them.

78.  Name the three major set of files on disk that compose a database in Oracle
There are three major sets of files on disk that compose a database. All the files are binary.  These are
Ø  Database files
Ø  Control files
Ø  Redo logs
The most important of these are the database files where the actual data resides. The control files and the redo logs support the functioning of the architecture itself.
All three sets of files must be present, open, and available to Oracle for any data on the database to be useable. Without these files, you cannot access the database, and the database administrator might have to recover some or all of the database using a backup, if there is one.

79.  What is an Oracle Instance?
The Oracle system processes, also known as Oracle background processes, provide functions for the user processes—functions that would otherwise be done by the user processes themselves
Oracle database-wide system memory is known as the SGA, the system global area or shared global area. The data and control structures in the SGA are shareable, and all the Oracle background processes and user processes can use them.
The combination of the SGA and the Oracle background processes is known as an Oracle instance

80.  What are the four Oracle system processes that must always be up and running for the database to be useable
            The four Oracle system processes that must always be up and running for the database to be useable include DBWR (Database Writer), LGWR (Log Writer), SMON (System Monitor), and PMON (Process Monitor).

81.  What are database files, control files and log files. How many of these files should a database have at least? Why?
Database Files
The database files hold the actual data and are typically the largest in size. Depending on their sizes, the tables (and other objects) for all the user accounts can go in one database file—but that's not an ideal situation because it does not make the database structure very flexible for controlling access to storage for different users, putting the database on different disk drives, or backing up and restoring just part of the database.
You must have at least one database file but usually, more than one files are used. In terms of accessing and using the data in the tables and other objects, the number (or location) of the files is immaterial.
The database files are fixed in size and never grow bigger than the size at which they were created
Control Files
The control files and redo logs support the rest of the architecture. Any database must have at least one control file, although you typically have more than one to guard against loss. The control file records the name of the database, the date and time it was created, the location of the database and redo logs, and the synchronization information to ensure that all three sets of files are always in step. Every time you add a new database or redo log file to the database, the information is recorded in the control files.
Redo Logs
Any database must have at least two redo logs. These are the journals for the database; the redo logs record all changes to the user objects or system objects. If any type of failure occurs, the changes recorded in the redo logs can be used to bring the database to a consistent state without losing any committed transactions. In the case of non-data loss failure, Oracle can apply the information in the redo logs automatically without intervention from the DBA.
The redo log files are fixed in size and never grow dynamically from the size at which they were created.

82.  What is ROWID?
            The ROWID is a unique database-wide physical address for every row on every table. Once assigned (when the row is first inserted into the database), it never changes until the row is deleted or the table is dropped.
The ROWID consists of the following three components, the combination of which uniquely identifies the physical storage location of the row.
Ø  Oracle database file number, which contains the block with the rows
Ø  Oracle block address, which contains the row
Ø  The row within the block (because each block can hold many rows)
The ROWID is used internally in indexes as a quick means of retrieving rows with a particular key value. Application developers also use it in SQL statements as a quick way to access a row once they know the ROWID

83.  What is Oracle Block? Can two Oracle Blocks have the same address?
            Oracle "formats" the database files into a number of Oracle blocks when they are first created—making it easier for the RDBMS software to manage the files and easier to read data into the memory areas.
The block size should be a multiple of the operating system block size. Regardless of the block size, the entire block is not available for holding data; Oracle takes up some space to manage the contents of the block. This block header has a minimum size, but it can grow.
These Oracle blocks are the smallest unit of storage. Increasing the Oracle block size can improve performance, but it should be done only when the database is first created.
Each Oracle block is numbered sequentially for each database file starting at 1. Two blocks can have the same block address if they are in different database files.

84.  What is database Trigger?
            A database trigger is a PL/SQL block that can defined to automatically execute for insert, update, and delete statements against a table. The trigger can e defined to execute once for the entire statement or once for every row that is inserted, updated, or deleted. For any one table, there are twelve events for which you can define database triggers. A database trigger can call database procedures that are also written in PL/SQL.

85.  Name two utilities that Oracle provides, which are use for backup and recovery.
            Along with the RDBMS software, Oracle provides two utilities that you can use to back up and restore the database. These utilities are Export and Import.
The Export utility dumps the definitions and data for the specified part of the database to an operating system binary file. The Import utility reads the file produced by an export, recreates the definitions of objects, and inserts the data
If Export and Import are used as a means of backing up and recovering the database, all the changes made to the database cannot be recovered since the export was performed. The best you can do is recover the database to the time when the export was last performed.

86.  What are stored-procedures? And what are the advantages of using them.
Stored procedures are database objects that perform a user defined operation. A stored procedure can have a set of compound SQL statements. A stored procedure executes the SQL commands and returns the result to the client. Stored procedures are used to reduce network traffic.

87.  How are exceptions handled in PL/SQL? Give some of the internal exceptions' name
            PL/SQL exception handling is a mechanism for dealing with run-time errors encountered during procedure execution. Use of this mechanism enables execution to continue if the error is not severe enough to cause procedure termination.
The exception handler must be defined within a subprogram specification. Errors cause the program to raise an exception with a transfer of control to the exception-handler block. After the exception handler executes, control returns to the block in which the handler was defined. If there are no more executable statements in the block, control returns to the caller.
User-Defined Exceptions
PL/SQL enables the user to define exception handlers in the declarations area of subprogram specifications. User accomplishes this by naming an exception as in the following example:
                                ot_failure  EXCEPTION;
In this case, the exception name is ot_failure. Code associated with this handler is written in the EXCEPTION specification area as follows:
EXCEPTION
      when OT_FAILURE then
        out_status_code := g_out_status_code;
        out_msg         := g_out_msg;
The following is an example of a subprogram exception:
EXCEPTION
      when NO_DATA_FOUND then
        g_out_status_code := 'FAIL';
        RAISE ot_failure;
Within this exception is the RAISE statement that transfers control back to the ot_failure exception handler. This technique of raising the exception is used to invoke all user-defined exceptions.
System-Defined Exceptions
Exceptions internal to PL/SQL are raised automatically upon error. NO_DATA_FOUND is a system-defined exception. Table below gives a complete list of internal exceptions.

PL/SQL internal exceptions.

Exception Name
Oracle Error
CURSOR_ALREADY_OPEN
ORA-06511
DUP_VAL_ON_INDEX
ORA-00001
INVALID_CURSOR
ORA-01001
INVALID_NUMBER
ORA-01722
LOGIN_DENIED
ORA-01017
NO_DATA_FOUND
ORA-01403
NOT_LOGGED_ON
ORA-01012
PROGRAM_ERROR
ORA-06501
STORAGE_ERROR
ORA-06500
TIMEOUT_ON_RESOURCE
ORA-00051
TOO_MANY_ROWS
ORA-01422
TRANSACTION_BACKED_OUT
ORA-00061
VALUE_ERROR
ORA-06502
ZERO_DIVIDE
ORA-01476

In addition to this list of exceptions, there is a catch-all exception named OTHERS that traps all errors for which specific error handling has not been established.

88.  Does PL/SQL support "overloading"? Explain
            The concept of overloading in PL/SQL relates to the idea that you can define procedures and functions with the same name. PL/SQL does not look only at the referenced name, however, to resolve a procedure or function call. The count and data types of formal parameters are also considered.
PL/SQL also attempts to resolve any procedure or function calls in locally defined packages before looking at globally defined packages or internal functions. To further ensure calling the proper procedure, you can use the dot notation. Prefacing a procedure or function name with the package name fully qualifies any procedure or function reference.

89.  Tables derived from the ERD
            a) Are totally unnormalised
            b) Are always in 1NF
            c) Can be further denormalised
            d) May have multi-valued attributes

 (b) Are always in 1NF

90.  Spurious tuples may occur due to
       i. Bad normalization 
      ii. Theta joins
     iii. Updating tables from join
            a) i & ii                                    b) ii & iii
            c) i & iii                                   d) ii & iii

 (a) i & iii  because  theta joins are joins made on keys that are not primary keys.

91.  A B C is a set of attributes. The functional dependency is as follows
      AB  ->   B
      AC ->    C
         C ->    B
            a) is in 1NF
            b) is in 2NF
            c) is in 3NF
            d) is in BCNF

 (a) is in 1NF since (AC)+ = { A, B, C} hence AC is the primary key. Since         C       B is a FD given, where neither C is a Key nor B is a prime attribute, this it is not in 3NF. Further B is not functionally dependent on key AC thus it is not in 2NF.  Thus the given FDs is in 1NF.

92.  In mapping of ERD to DFD
            a) entities in ERD should correspond to an existing entity/store in DFD
            b) entity in DFD is converted to attributes of an entity in ERD
            c) relations in ERD has 1 to 1 correspondence to processes in DFD
            d) relationships in ERD has 1 to 1 correspondence to flows in DFD

 (a) entities in ERD should correspond to an existing entity/store in DFD

93.  A dominant entity is the entity
            a) on the N side in a 1 : N relationship
            b) on the 1 side in a 1 : N relationship
            c) on either side in a 1 : 1 relationship
            d) nothing to do with 1 : 1 or 1 : N relationship

(b) on the 1 side in a 1 : N relationship

94.  Select  'NORTH', CUSTOMER From CUST_DTLS Where REGION = 'N' Order By
CUSTOMER Union Select  'EAST', CUSTOMER From CUST_DTLS Where REGION = 'E' Order By CUSTOMER
The above is
            a) Not an error
            b) Error - the string in single quotes 'NORTH' and 'SOUTH'
            c) Error - the string should be in double quotes
            d) Error -  ORDER BY clause

(d)  Error - the ORDER BY clause. Since ORDER BY clause cannot be used in UNIONS

95.  What is Storage Manager? 
It is a program module that provides the interface between the low-level data stored in database, application programs and queries submitted to the system.   
 
96.  What is Buffer Manager?
It is a program module, which is responsible for fetching data from disk storage into main memory and deciding what data to be cache in memory. 

97.  What is Transaction Manager?
It is a program module, which ensures that database, remains in a consistent state despite system failures and concurrent transaction execution proceeds without conflicting.

98.  What is File Manager?
It is a program module, which manages the allocation of space on disk storage and data structure used to represent information stored on a disk.  

99.  What is Authorization and Integrity manager?
It is the program module, which tests for the satisfaction of integrity constraint and checks the authority of user to access data.   

100.          What are stand-alone procedures?
Procedures that are not part of a package are known as stand-alone because they independently defined. A good example of a stand-alone procedure is one written in a SQL*Forms application. These types of procedures are not available for reference from other Oracle tools. Another limitation of stand-alone procedures is that they are compiled at run time, which slows execution.

101.          What are cursors give different types of cursors.
PL/SQL uses cursors for all database information accesses statements. The language supports the use two types of cursors
Ø  Implicit
Ø  Explicit

102.          What is cold backup and hot backup (in case of Oracle)?
Ø  Cold Backup:
It is copying the three sets of files (database files, redo logs, and control file) when the instance is shut down. This is a straight file copy, usually from the disk directly to tape. You must shut down the instance to guarantee a consistent copy.
If a cold backup is performed, the only option available in the event of data file loss is restoring all the files from the latest backup. All work performed on the database since the last backup is lost.
Ø  Hot Backup:
Some sites (such as worldwide airline reservations systems) cannot shut down the database while making a backup copy of the files. The cold backup is not an available option.
So different means of backing up database must be used — the hot backup. Issue a SQL command to indicate to Oracle, on a tablespace-by-tablespace basis, that the files of the tablespace are to backed up. The users can continue to make full use of the files, including making changes to the data. Once the user has indicated that he/she wants to back up the tablespace files, he/she can use the operating system to copy those files to the desired backup destination.
The database must be running in ARCHIVELOG mode for the hot backup option.
If a data loss failure does occur, the lost database files can be restored using the hot backup and the online and offline redo logs created since the backup was done. The database is restored to the most consistent state without any loss of committed transactions.

103.          What are Armstrong rules? How do we say that they are complete and/or sound
The well-known inference rules for FDs        
Ø  Reflexive rule : 
                                    If Y is subset or equal to X then X       Y.
Ø  Augmentation rule:
                                    If X       Y then XZ       YZ.
Ø  Transitive rule:
                                    If  {X      Y, Y       Z} then X        Z.
Ø  Decomposition rule :
                                    If X       YZ then X       Y.
Ø  Union or Additive rule:
                                    If {X      Y, X        Z} then X       YZ.
Ø  Pseudo Transitive rule :
                                    If {X      Y, WY         Z} then WX        Z.
            Of these the first three are known as Amstrong Rules. They are sound because it is enough if a set of FDs satisfy these three. They are called complete because using these three rules we can generate the rest all inference rules.

104.          How can you find the minimal key of relational schema?
Minimal key is one which can identify each tuple of the given relation schema uniquely. For finding the minimal key it is required to find the closure that is the set of all attributes that are dependent on any given set of attributes under the given set of functional dependency.
            Algo. I Determining X+, closure for X, given set of FDs F
1.      Set X+ = X
2.      Set Old X+ = X+
3.      For each FD  Y        Z in F and if  Y belongs to X+ then add Z to X+
4.      Repeat steps 2 and 3 until Old X+  = X+

Algo.II Determining minimal K for relation schema R, given set of FDs F
1.      Set K to R that is make K a set of all attributes in R
2.      For each attribute A in K
a.       Compute (K – A)+ with respect to F
b.      If  (K – A)+ = R then set K = (K – A)+


105.          What do you understand by dependency preservation?
Given a relation R and a set of FDs F, dependency preservation states that the closure of  the union of the projection of F on each decomposed relation Ri is equal to the closure of F. i.e.,
((PR1(F))  U … U (PRn(F)))+ =  F+
 if decomposition is not dependency preserving, then some dependency is lost in the decomposition.

106.          What is meant by Proactive, Retroactive and Simultaneous Update.
Proactive Update:
            The updates that are applied to database before it becomes effective in real world .
Retroactive Update:
            The updates that are applied to database after it becomes effective in real world .
Simulatneous Update:
            The updates that are applied to database at the same time when it becomes effective in real world .

107.          What are the different types of JOIN operations?
Equi Join:  This is the most common type of join which involves only equality comparisions. The disadvantage in this type of join is that there