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2012-03-20T22:56:00.002-07:00

C# (C Sharp) Question:-

1.What is C#?

C# (pronounced "C sharp") is a simple, modern, object-oriented, and type-safe programming language.
It will immediately be familiar to C and C++ programmers.

C# combines the high productivity of Rapid Application Development (RAD) languages.

2. What are the types of comment in C#?

There are 3 types of comments in C#.

Single line (//)
Multi (/* */)
Page/XML Comments (///).

3.What are the namespaces used in C#.NET?

Namespace is a logical grouping of class.

using System;
using System.Collections.Generic;
using System.Windows.Forms;

4.What are the characteristics of C#?

There are several characteristics of C# are :

Simple
Type safe
Flexible
Object oriented
Compatible
Consistent
Interoperable
Modern

5.How does C# differ from C++?

C# does not support #include statement. It uses only using statement.
In C# , class definition does not use a semicolon at the end.
C# does not support multiple code inheritance.
Casting in C# is much safer than in c++.
In C# switch can also be used on string values.
Command line parameters array behave differently in C# as compared to C++.

6.What are the basic concepts of object oriented programming?

It is necessary to understand some of the concepts used extensively in object oriented programming.These include

Objects
Classes
Data abstraction and encapsulation
Inheritance
Polymorphism
Dynamic Binding
Message passing.

7.Can you inherit multiple interfaces?

Yes. Multiple interfaces may be inherited in C#.

8.What is inheritance?

Inheritance is deriving the new class from the already existing one.

9.Define scope?

Scope refers to the region of code in which a variable may be accessed

10.What is the difference between public, static and void?

public :The keyword public is an access modifier that tells the C# compiler that the Main method is accessible by anyone.
static :The keyword static declares that the Main method is a global one and can be called without creating an instance of the class. The compiler stores the address of the method as the entry point and uses this information to begin execution before any objects are created.
void : The keyword void is a type modifier that states that the Main method does not return any value.

11.What are the modifiers in C#?

Abstract
Sealed
Virtual
Const
Event
Extern
Override
Readonly
Static
New

12.What are the types of access modifiers in C#?

Access modifiers in C# are :

public
protect
private
internal
internal protect

13.What is boxing and unboxing?

Implicit conversion of value type to reference type of a variable is known as BOXING, for example integer to object type conversion.
Conversion of reference type variable back to value type is called as UnBoxing.

14What is object?

An object is an instance of a class. An object is created by using operator new. A class that creates an object in memory will contain the information about the values and behaviours (or methods) of that specific object.

15.Where are the types of arrays in C#?

Single-Dimensional
Multidimensional
Jagged arrays.

16.What is the difference between Object and Instance?

An instance of a user-defined type is called an object. We can instantiate many objects from one class.
An object is an instance of a class.

17.Define destuctors?

A destructor is called for a class object when that object passes out of scope or is explicitly deleted.A destructors as the name implies is used to destroy the objects that have been created by a constructors.Like a constructor , the destructor is a member function whose name is the same as the class name but is precided by a tilde.

18.What is the use of enumerated data type?

An enumerated data type is another user defined type which provides a way for attaching names to numbers thereby increasing comprehensibility of the code. The enum keyword automatically enumerates a list of words by assigning them values 0,1,2, and so on.

19.Define Constructors?

A constructor is a member function with the same name as its class. The constructor is invoked whenever an object of its associated class is created.It is called constructor because it constructs the values of data members of the class.

20.What is encapsulation?

The wrapping up of data and functions into a single unit (called class) is known as encapsulation. Encapsulation containing and hiding information about an object, such as internal data structures and code.

21.Does c# support multiple inheritance?

No,its impossible which accepts multi level inheritance.

22.What is ENUM?

Enum are used to define constants

23.What is a data set?

A DataSet is an in memory representation of data loaded from any data source

24.What is the difference between private and public keyword?

Private : The private keyword is the default access level and most restrictive among all other access levels. It gives least permission to a type or type member. A private member is accessible only within the body of the class in which it is declared.
Public : The public keyword is most liberal among all access levels, with no restrictions to access what so ever. A public member is accessible not only from within, but also from outside, and gives free access to any member declared within the body or outside the body.

25.Define polymorphism?

Polymorphism means one name, multiple forms. It allows us to have more than one function with the same name in a program.It allows us to have overloading of operators so that an operation can exhibit different behaviours in different instances.

26.What is Jagged Arrays?

A jagged array is an array whose elements are arrays.
The elements of a jagged array can be of different dimensions and sizes.
A jagged array is sometimes called an array–of–arrays.

27.what is an abstract base class?

An abstract class is a class that is designed to be specifically used as a base class. An abstract class contains at least one pure virtual function.

28.How is method overriding different from method overloading?

When overriding a method, you change the behavior of the method for the derived class. Overloading a method simply involves having another method with the same name within the class.

29.What is the difference between ref & out parameters?

An argument passed to a ref parameter must first be initialized. Compare this to an out parameter, whose argument does not have to be explicitly initialized before being passed to an out parameter.

30.What is the use of using statement in C#?

The using statement is used to obtain a resource, execute a statement, and then dispose of that resource.

31.What is serialization?

Serialization is the process of converting an object into a stream of bytes.
De-serialization is the opposite process of creating an object from a stream of bytes.
Serialization / De-serialization is mostly used to transport objects.

32.What are the difference between Structure and Class?

Structures are value type and Classes are reference type
Structures can not have contractors or destructors.
Classes can have both contractors and destructors.
Structures do not support Inheritance, while Classes support Inheritance.

33.What is difference between Class And Interface?

Class : is logical representation of object. It is collection of data and related sub procedures with defination.
Interface : is also a class containg methods which is not having any definations.Class does not support multiple inheritance. But interface can support.

34.What is Delegates?

Delegates are a type-safe, object-oriented implementation of function pointers and are used in many situations where a component needs to call back to the component that is using it.

35.What is Authentication and Authorization?

Authentication is the process of identifying users. Authentication is identifying/validating the user against the credentials (username and password).
Authorization performs after authentication. Authorization is the process of granting access to those users based on identity. Authorization allowing access of specific resource to user

36.What is a base class?

A class declaration may specify a base class by following the class name with a colon and the name of the base class. omitting a base class specification is the same as deriving from type object.

37.Can “this” be used within a static method?

No ‘This’ cannot be used in a static method. As only static variables/methods can be used in a static method.

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2012-03-20T22:55:00.000-07:00

38.What is difference between constants, readonly and, static ?

Constants: The value can’t be changed.
Read-only: The value will be initialized only once from the constructor of the class.
Static: Value can be initialized once.

39.What are the different types of statements supported in C#?

C# supports several different kinds of statements are

Block statements
Declaration statements
Expression statements
Selection statements
Iteration statements
Jump statements
Try catch statements
Checked and unchecked
Lock statement

40.What is an interface class?

It is an abstract class with public abstract methods all of which must be implemented in the inherited classes.

41.what are value types and reference types?

Value types are stored in the Stack.
Examples : bool, byte, chat, decimal, double, enum , float, int, long, sbyte, short, strut, uint, ulong, ushort.

Reference types are stored in the Heap.
Examples : class, delegate, interface, object, string.

42.What is the difference between string keyword and System.String class?

String keyword is an alias for Syste.String class. Therefore, System.String and string keyword are the same, and you can use whichever naming convention you prefer. The String class provides many methods for safely creating, manipulating, and comparing strings.

43.What are the two data types available in C#?

Value type
Reference type

44.What are the different types of Caching?

There are three types of Caching :

Output Caching: stores the responses from an asp.net page.
Fragment Caching: Only caches/stores the portion of page (User Control)
Data Caching: is Programmatic way to Cache objects for performance.

45.What is the difference between Custom Control and User Control?

Custom Controls are compiled code (Dlls), easier to use, difficult to create, and can be placed in toolbox. Drag and Drop controls. Attributes can be set visually at design time. Can be used by Multiple Applications (If Shared Dlls), Even if Private can copy to bin directory of web application add reference and use. Normally designed to provide common functionality independent of consuming Application.

User Controls are similar to those of ASP include files, easy to create, can not be placed in the toolbox and dragged - dropped from it. A User Control is shared among the single application files

46.What is methods?

A method is a member that implements a computation or action that can be performed by an object or class. Static methods are accessed through the class. Instance methods are accessed through instances of the class.

47.What is fields?

A field is a variable that is associated with a class or with an instance of a class.

48.What is events?

An event is a member that enables a class or object to provide notifications. An event is declared like a field except that the declaration includes an event keyword and the type must be a delegate type.

49.What is literals and their types?

Literals are value constants assigned to variables in a program. C# supports several types of literals are

Integer literals
Real literals
Boolean literals
Single character literals
String literals
Backslash character literals

50.What is the difference between value type and reference type?

Value types are stored on the stack and when a value of a variable is assigned to another variable.
Reference types are stored on the heap, and when an assignment between two reference variables occurs.

51.What are the features of c#?

C# is a simple and powerful programming language for writing enterprise edition applications.
This is a hybrid of C++ and VB. It retains many C++ features in the area statements,expressions, and operators and incorporated the productivity of VB.
C# helps the developers to easily build the web services that can be used across the Internet through any language, on any platform.
C# helps the developers accomplishing with fewer lines of code that will lead to the fewer errors in the code.
C# introduces the considerable improvement and innovations in areas such as type safety,versioning. events and garbage collections.

52.What are the types of errors?

Syntax error
Logic error
Runtime error

53.What is the difference between break and continue statement?

The break statement is used to terminate the current enclosing loop or conditional statements in which it appears. We have already used the break statement to come out of switch statements.
The continue statement is used to alter the sequence of execution. Instead of coming out of the loop like the break statement did, the continue statement stops the current iteration and simply returns control back to the top of the loop.

54.Define namespace?

The namespace are known as containers which will be used to organize the hierarchical set of .Net classes.

55.What is a code group?

A code group is a set of assemblies that share a security context.

56.What are sealed classes in C#?

The sealed modifier is used to prevent derivation from a class. A compile-time error occurs if a sealed class is specified as the base class of another class.

57.What is the difference between static and instance methods?

A method declared with a static modifier is a static method. A static method does not operate on a specific instance and can only access static members.

A method declared without a static modifier is an instance method. An instance method operates on a specific instance and can access both static and instance members. The instance on which an instance method was invoked can be explicitly accessed as this. It is an error to refer to this in a static method.

58.What are the different types of variables in C#?

Different types of variables used in C# are :

static variables
instance variable
value parameters
reference parameters
array elements
output parameters
local variables

59.What is meant by method overloading?

Method overloading permits multiple methods in the same class to have the same name as long as they have unique signatures. When compiling an invocation of an overloaded method, the compiler uses overload resolution to determine the specific method to invoke

60.What is parameters?

Parameters are used to pass values or variable references to methods. The parameters of a method get their actual values from the arguments that are specified when the method is invoked. There are four kinds of parameters: value parameters, reference parameters, output parameters, and parameter arrays.

61.Is C# is object oriented?

YEs, C# is an OO langauge in the tradition of Java and C++.

62.What is the difference between Array and Arraylist?

An array is a collection of the same type. The size of the array is fixed in its declaration. A linked list is similar to an array but it doesn’t have a limited size.

63.What are the special operators in C#?

C# supports the following special operators.

is (relational operator)
as (relational operator)
typeof (type operator)
sizeof (size operator)
new (object creator)
.dot (member access operator)
checked (overflow checking)
unchecked (prevention of overflow checking)

64.What is meant by operators in c#?

An operator is a member that defines the meaning of applying a particular expression operator to instances of a class. Three kinds of operators can be defined: unary operators, binary operators, and conversion operators. All operators must be declared as public and static.

65.What is a parameterized type?

A parameterized type is a type that is parameterized over another value or type.

66.What are the features of abstract class?

An abstract class cannot be instantiated, and it is an error to use the new operator on an abstract class.
An abstract class is permitted (but not required) to contain abstract methods and accessors.
An abstract class cannot be scaled.

67.What is the use of abstract keyword?

The modifier abstract is a keyword used with a class, to indicate that this class cannot itself have direct instances or objects, and it is intended to be only a 'base' class to other classes.

68.What is the use of goto statement?

The goto statement is also included in the C# language. This goto can be used to jump from inside a loop to outside. But jumping from outside to inside a loop is not allowed.

69What is the difference between console and window application?

A console application, which is designed to run at the command line with no user interface.
A Windows application, which is designed to run on a user’s desktop and has a user interface.

70.What is the use of return statement?

The return statement is associated with procedures (methods or functions). On executing the return statement, the system passes the control from the called procedure to the calling procedure. This return statement is used for two purposes :

· to return immediately to the caller of the currently executed code

· to return some value to the caller of the currently executed code.

71.What is the difference between Array and LinkedList?

Array is a simple sequence of numbers which are not concerned about each others positions. they are independent of each others positions. adding,removing or modifying any array element is very easy. Compared to arrays ,linked list is a comlicated sequence of numbers.

72.Does C# have a throws clause?

No, unlike Java, C# does not require the developer to specify the exceptions that a method can throw.

73.Does C# support a variable number of arguments?

Yes, uisng the params keyword. The arguments are specified as a list of arguments of a specific type.

74.Can you override private virtual methods?

No, private methods are not accessible outside the class.

75What is a multi cast delegates?

It is a delegate that points to and eventually fires off several methods.

2012-03-14T22:58:00.001-07:00

JAVA:-

1. What is the most important feature of Java?

Java is a platform independent language.

2. What do you mean by platform independence?

Platform independence means that we can write and compile the java code in one platform (eg Windows) and can execute the class in any other supported platform eg (Linux,Solaris,etc).

3. What is a JVM?

JVM is Java Virtual Machine which is a run time environment for the compiled java class files.

4. Are JVM's platform independent?

JVM's are not platform independent. JVM's are platform specific run time implementation provided by the vendor.

5. What is the difference between a JDK and a JVM?

JDK is Java Development Kit which is for development purpose and it includes execution environment also. But JVM is purely a run time environment and hence you will not be able to compile your source files using a JVM.

6. What is a pointer and does Java support pointers?

Pointer is a reference handle to a memory location. Improper handling of pointers leads to memory leaks and reliability issues hence Java doesn't support the usage of pointers.

7. What is the base class of all classes?

java.lang.Object

8. Does Java support multiple inheritance?

Java doesn't support multiple inheritance.

9. Is Java a pure object oriented language?

Java uses primitive data types and hence is not a pure object oriented language.

10. Are arrays primitive data types?

In Java, Arrays are objects.

11. What is difference between Path and Classpath?

Path and Classpath are operating system level environment variales. Path is used define where the system can find the executables(.exe) files and classpath is used to specify the location .class files.

12. What are local variables?

Local varaiables are those which are declared within a block of code like methods. Local variables should be initialised before accessing them.

13. What are instance variables?

Instance variables are those which are defined at the class level. Instance variables need not be initialized before using them as they are automatically initialized to their default values.

14. How to define a constant variable in Java?

The variable should be declared as static and final. So only one copy of the variable exists for all instances of the class and the value can't be changed also.
static final int PI = 2.14; is an example for constant.

15. Should a main() method be compulsorily declared in all java classes?

No not required. main() method should be defined only if the source class is a java application.

16. What is the return type of the main() method?

Main() method doesn't return anything hence declared void.

17. Why is the main() method declared static?

main() method is called by the JVM even before the instantiation of the class hence it is declared as static.

18. What is the arguement of main() method?

main() method accepts an array of String object as arguement.

19. Can a main() method be overloaded?

Yes. You can have any number of main() methods with different method signature and implementation in the class.

20. Can a main() method be declared final?

Yes. Any inheriting class will not be able to have it's own default main() method.

21. Does the order of public and static declaration matter in main() method?

No. It doesn't matter but void should always come before main().

22. Can a source file contain more than one class declaration?

Yes a single source file can contain any number of Class declarations but only one of the class can be declared as public.

23. What is a package?

Package is a collection of related classes and interfaces. package declaration should be first statement in a java class.

24. Which package is imported by default?

java.lang package is imported by default even without a package declaration.

25. Can a class declared as private be accessed outside it's package?

Not possible.

26. Can a class be declared as protected?

A class can't be declared as protected. only methods can be declared as protected.

27. What is the access scope of a protected method?

A protected method can be accessed by the classes within the same package or by the subclasses of the class in any package.

28. What is the purpose of declaring a variable as final?

A final variable's value can't be changed. final variables should be initialized before using them.

29. What is the impact of declaring a method as final?

A method declared as final can't be overridden. A sub-class can't have the same method signature with a different implementation.

30. I don't want my class to be inherited by any other class. What should i do?

You should declared your class as final. But you can't define your class as final, if it is an abstract class. A class declared as final can't be extended by any other class.

31. Can you give few examples of final classes defined in Java API?

java.lang.String, java.lang.Math are final classes.

32. How is final different from finally and finalize()?

final is a modifier which can be applied to a class or a method or a variable. final class can't be inherited, final method can't be overridden and final variable can't be changed.

finally is an exception handling code section which gets executed whether an exception is raised or not by the try block code segment.

finalize() is a method of Object class which will be executed by the JVM just before garbage collecting object to give a final chance for resource releasing activity.

33. Can a class be declared as static?

No a class cannot be defined as static. Only a method, a variable or a block of code can be declared as static.

34. When will you define a method as static?

When a method needs to be accessed even before the creation of the object of the class then we should declare the method as static.

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2012-03-14T22:57:00.000-07:00

35. What are the restriction imposed on a static method or a static block of code?

A static method should not refer to instance variables without creating an instance and cannot use "this" operator to refer the instance.

36. I want to print "Hello" even before main() is executed. How will you acheive that?

Print the statement inside a static block of code. Static blocks get executed when the class gets loaded into the memory and even before the creation of an object. Hence it will be executed before the main() method. And it will be executed only once.

37. What is the importance of static variable?

static variables are class level variables where all objects of the class refer to the same variable. If one object changes the value then the change gets reflected in all the objects.

38. Can we declare a static variable inside a method?

Static varaibles are class level variables and they can't be declared inside a method. If declared, the class will not compile.

39. What is an Abstract Class and what is it's purpose?

A Class which doesn't provide complete implementation is defined as an abstract class. Abstract classes enforce abstraction.

40. Can a abstract class be declared final?

Not possible. An abstract class without being inherited is of no use and hence will result in compile time error.

41. What is use of a abstract variable?

Variables can't be declared as abstract. only classes and methods can be declared as abstract.

42. Can you create an object of an abstract class?

Not possible. Abstract classes can't be instantiated.

43. Can a abstract class be defined without any abstract methods?

Yes it's possible. This is basically to avoid instance creation of the class.

44. Class C implements Interface I containing method m1 and m2 declarations. Class C has provided implementation for method m2. Can i create an object of Class C?

No not possible. Class C should provide implementation for all the methods in the Interface I. Since Class C didn't provide implementation for m1 method, it has to be declared as abstract. Abstract classes can't be instantiated.

45. Can a method inside a Interface be declared as final?

No not possible. Doing so will result in compilation error. public and abstract are the only applicable modifiers for method declaration in an interface.

46. Can an Interface implement another Interface?

Intefaces doesn't provide implementation hence a interface cannot implement another interface.

47. Can an Interface extend another Interface?

Yes an Interface can inherit another Interface, for that matter an Interface can extend more than one Interface.

48. Can a Class extend more than one Class?

Not possible. A Class can extend only one class but can implement any number of Interfaces.

49. Why is an Interface be able to extend more than one Interface but a Class can't extend more than one Class?

Basically Java doesn't allow multiple inheritance, so a Class is restricted to extend only one Class. But an Interface is a pure abstraction model and doesn't have inheritance hierarchy like classes(do remember that the base class of all classes is Object). So an Interface is allowed to extend more than one Interface.

50. Can an Interface be final?

Not possible. Doing so so will result in compilation error.

51. Can a class be defined inside an Interface?

Yes it's possible.

52. Can an Interface be defined inside a class?

Yes it's possible.

53. What is a Marker Interface?

An Interface which doesn't have any declaration inside but still enforces a mechanism.

54. Which object oriented Concept is achieved by using overloading and overriding?

Polymorphism.

55. Why does Java not support operator overloading?

Operator overloading makes the code very difficult to read and maintain. To maintain code simplicity, Java doesn't support operator overloading.

56. Can we define private and protected modifiers for variables in interfaces?

No.

57. What is Externalizable?

Externalizable is an Interface that extends Serializable Interface. And sends data into Streams in Compressed Format. It has two methods, writeExternal(ObjectOuput out) and readExternal(ObjectInput in)

58. What modifiers are allowed for methods in an Interface?

Only public and abstract modifiers are allowed for methods in interfaces.

59. What is a local, member and a class variable?

Variables declared within a method are "local" variables.

Variables declared within the class i.e not within any methods are "member" variables (global variables).

Variables declared within the class i.e not within any methods and are defined as "static" are class variables.

60. What is an abstract method?

An abstract method is a method whose implementation is deferred to a subclass.

61. What value does read() return when it has reached the end of a file?

The read() method returns -1 when it has reached the end of a file.

62. Can a Byte object be cast to a double value?

No, an object cannot be cast to a primitive value.

63. What is the difference between a static and a non-static inner class?

A non-static inner class may have object instances that are associated with instances of the class's outer class. A static inner class does not have any object instances.

64. What is an object's lock and which object's have locks?

An object's lock is a mechanism that is used by multiple threads to obtain synchronized access to the object. A thread may execute a synchronized method of an object only after it has acquired the object's lock. All objects and classes have locks. A class's lock is acquired on the class's Class object.

65. What is the % operator?

It is referred to as the modulo or remainder operator. It returns the remainder of dividing the first operand by the second operand.

66. When can an object reference be cast to an interface reference?

An object reference be cast to an interface reference when the object implements the referenced interface.

67. Which class is extended by all other classes?

The Object class is extended by all other classes.

68. Which non-Unicode letter characters may be used as the first character of an identifier?

The non-Unicode letter characters $ and _ may appear as the first character of an identifier

69. What restrictions are placed on method overloading?

Two methods may not have the same name and argument list but different return types.

70. What is casting?

There are two types of casting, casting between primitive numeric types and casting between object references. Casting between numeric types is used to convert larger values, such as double values, to smaller values, such as byte values. Casting between object references is used to refer to an object by a compatible class, interface, or array type reference.

71. What is the return type of a program's main() method?

void.

72. If a variable is declared as private, where may the variable be accessed?

A private variable may only be accessed within the class in which it is declared.

73. What do you understand by private, protected and public?

These are accessibility modifiers. Private is the most restrictive, while public is the least restrictive. There is no real difference between protected and the default type (also known as package protected) within the context of the same package, however the protected keyword allows visibility to a derived class in a different package.

74. What is Downcasting ?

Downcasting is the casting from a general to a more specific type, i.e. casting down the hierarchy

75. What modifiers may be used with an inner class that is a member of an outer class?

A (non-local) inner class may be declared as public, protected, private, static, final, or abstract.

76. How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?

Unicode requires 16 bits and ASCII require 7 bits Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits.

UTF-8 represents characters using 8, 16, and 18 bit patterns.

UTF-16 uses 16-bit and larger bit patterns.

77. What restrictions are placed on the location of a package statement within a source code file?

A package statement must appear as the first line in a source code file (excluding blank lines and comments).

78. What is a native method?

A native method is a method that is implemented in a language other than Java.

79. What are order of precedence and associativity, and how are they used?

Order of precedence determines the order in which operators are evaluated in expressions. Associatity determines whether an expression is evaluated left-to-right or right-to-left.

80. Can an anonymous class be declared as implementing an interface and extending a class?

An anonymous class may implement an interface or extend a superclass, but may not be declared to do both.

81. What is the range of the char type?

The range of the char type is 0 to 2¹⁶ - 1 (i.e. 0 to 65535.)

82. What is the range of the short type?

The range of the short type is -(2¹⁵) to 2¹⁵ - 1. (i.e. -32,768 to 32,767)

83. Why isn't there operator overloading?

Because C++ has proven by example that operator overloading makes code almost impossible to maintain.

84. What does it mean that a method or field is "static"?

Static variables and methods are instantiated only once per class. In other words they are class variables, not instance variables. If you change the value of a static variable in a particular object, the value of that variable changes for all instances of that class. Static methods can be referenced with the name of the class rather than the name of a particular object of the class (though that works too). That's how library methods like System.out.println() work. out is a static field in the java.lang.System class.

85. Is null a keyword?

The null value is not a keyword.

86. Which characters may be used as the second character of an identifier, but not as the first character of an identifier?

The digits 0 through 9 may not be used as the first character of an identifier but they may be used after the first character of an identifier.

87. Is the ternary operator written x : y ? z or x ? y : z ?

It is written x ? y : z.

88. How is rounding performed under integer division?

The fractional part of the result is truncated. This is known as rounding toward zero.

89. If a class is declared without any access modifiers, where may the class be accessed?

A class that is declared without any access modifiers is said to have package access. This means that the class can only be accessed by other classes and interfaces that are defined within the same package.

90. Does a class inherit the constructors of its superclass?

A class does not inherit constructors from any of its superclasses.

91. Name the eight primitive Java types.

The eight primitive types are byte, char, short, int, long, float, double, and boolean.

92. What restrictions are placed on the values of each case of a switch statement?

During compilation, the values of each case of a switch statement must evaluate to a value that can be promoted to an int value.

93. What is the difference between a while statement and a do while statement?

A while statement checks at the beginning of a loop to see whether the next loop iteration should occur. A do while statement checks at the end of a loop to see whether the next iteration of a loop should occur. The do whilestatement will always execute the body of a loop at least once.

94. What modifiers can be used with a local inner class?

A local inner class may be final or abstract.

95. When does the compiler supply a default constructor for a class?

The compiler supplies a default constructor for a class if no other constructors are provided.

96. If a method is declared as protected, where may the method be accessed?

A protected method may only be accessed by classes or interfaces of the same package or by subclasses of the class in which it is declared.

97. What are the legal operands of the instanceof operator?

The left operand is an object reference or null value and the right operand is a class, interface, or array type.

continue....

2012-03-14T22:24:00.003-07:00

98. Are true and false keywords?

The values true and false are not keywords.

99. What happens when you add a double value to a String?

The result is a String object.

100. What is the diffrence between inner class and nested class?

When a class is defined within a scope od another class, then it becomes inner class. If the access modifier of the inner class is static, then it becomes nested class.

101. Can an abstract class be final?

An abstract class may not be declared as final.

102. What is numeric promotion?

Numeric promotion is the conversion of a smaller numeric type to a larger numeric type, so that integer and floating-point operations may take place. In numerical promotion, byte, char, and short values are converted to int values. The int values are also converted to long values, if necessary. The long and float values are converted to double values, as required.

103. What is the difference between a public and a non-public class?

A public class may be accessed outside of its package. A non-public class may not be accessed outside of its package.

104. To what value is a variable of the boolean type automatically initialized?

The default value of the boolean type is false.

105. What is the difference between the prefix and postfix forms of the ++ operator?

The prefix form performs the increment operation and returns the value of the increment operation. The postfix form returns the current value all of the expression and then performs the increment operation on that value.

106. What restrictions are placed on method overriding?

Overridden methods must have the same name, argument list, and return type. The overriding method may not limit the access of the method it overrides. The overriding method may not throw any exceptions that may not be thrown by the overridden method.

107. What is a Java package and how is it used?

A Java package is a naming context for classes and interfaces. A package is used to create a separate name space for groups of classes and interfaces. Packages are also used to organize related classes and interfaces into a single API unit and to control accessibility to these classes and interfaces.

108. What modifiers may be used with a top-level class?

A top-level class may be public, abstract, or final.

109. What is the difference between an if statement and a switch statement?

The if statement is used to select among two alternatives. It uses a boolean expression to decide which alternative should be executed. The switch statement is used to select among multiple alternatives. It uses an int expression to determine which alternative should be executed.

110. What are the practical benefits, if any, of importing a specific class rather than an entire package (e.g. import java.net.* versus import java.net.Socket)?

It makes no difference in the generated class files since only the classes that are actually used are referenced by the generated class file. There is another practical benefit to importing single classes, and this arises when two (or more) packages have classes with the same name. Take java.util.Timer and javax.swing.Timer, for example. If I import java.util.* and javax.swing.* and then try to use "Timer", I get an error while compiling (the class name is ambiguous between both packages). Let's say what you really wanted was the javax.swing.Timer class, and the only classes you plan on using in java.util are Collection and HashMap. In this case, some people will prefer to import java.util.Collection and import java.util.HashMap instead of importing java.util.*. This will now allow them to use Timer, Collection, HashMap, and other javax.swing classes without using fully qualified class names in.

111. Can a method be overloaded based on different return type but same argument type ?

No, because the methods can be called without using their return type in which case there is ambiquity for the compiler.

112. What happens to a static variable that is defined within a method of a class ?

Can't do it. You'll get a compilation error.

113. How many static initializers can you have ?

As many as you want, but the static initializers and class variable initializers are executed in textual order and may not refer to class variables declared in the class whose declarations appear textually after the use, even though these class variables are in scope.

114. What is the difference between method overriding and overloading?

Overriding is a method with the same name and arguments as in a parent, whereas overloading is the same method name but different arguments

115. What is constructor chaining and how is it achieved in Java ?

A child object constructor always first needs to construct its parent (which in turn calls its parent constructor.). In Java it is done via an implicit call to the no-args constructor as the first statement.

116. What is the difference between the Boolean & operator and the && operator?

If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the first operand is evaluated. If the first operand returns a value of true then the second operand is evaluated. The && operator is then applied to the first and second operands. If the first operand evaluates to false, the evaluation of the second operand is skipped.

117. Which Java operator is right associative?

The = operator is right associative.

118. Can a double value be cast to a byte?

Yes, a double value can be cast to a byte.

119. What is the difference between a break statement and a continue statement?

A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.

120. Can a for statement loop indefinitely?

Yes, a for statement can loop indefinitely. For example, consider the following: for(;;);

121. To what value is a variable of the String type automatically initialized?

The default value of an String type is null.

122. What is the difference between a field variable and a local variable?

A field variable is a variable that is declared as a member of a class. A local variable is a variable that is declared local to a method.

123. How are this() and super() used with constructors?

this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.

124. What does it mean that a class or member is final?

A final class cannot be inherited. A final method cannot be overridden in a subclass. A final field cannot be changed after it's initialized, and it must include an initializer statement where it's declared.

125. What does it mean that a method or class is abstract?

An abstract class cannot be instantiated. Abstract methods may only be included in abstract classes. However, an abstract class is not required to have any abstract methods, though most of them do. Each subclass of an abstract class must override the abstract methods of its superclasses or it also should be declared abstract.

126. What is a transient variable?

Transient variable is a variable that may not be serialized.

127. How does Java handle integer overflows and underflows?

It uses those low order bytes of the result that can fit into the size of the type allowed by the operation.

128. What is the difference between the >> and >>> operators?

The >> operator carries the sign bit when shifting right. The >>> zero-fills bits that have been shifted out.

129. Is sizeof a keyword?

The sizeof operator is not a keyword.

2012-03-14T22:12:00.000-07:00

DATA STRUCTURE:-

1. What is data structure?

A data structure is a way of organizing data that considers not only the items stored, but also their relationship to each other. Advance knowledge about the relationship between data items allows designing of efficient algorithms for the manipulation of data.

2. List out the areas in which data structures are applied extensively?

Compiler Design,
Operating System,
Database Management System,
Statistical analysis package,
Numerical Analysis,
Graphics,
Artificial Intelligence,
Simulation

3. What are the major data structures used in the following areas : RDBMS, Network data model and Hierarchical data model.

RDBMS = Array (i.e. Array of structures)
Network data model = Graph
Hierarchical data model = Trees

4. If you are using C language to implement the heterogeneous linked list, what pointer type will you use?

The heterogeneous linked list contains different data types in its nodes and we need a link, pointer to connect them. It is not possible to use ordinary pointers for this. So we go for void pointer. Void pointer is capable of storing pointer to any type as it is a generic pointer type.

5. Minimum number of queues needed to implement the priority queue?

Two. One queue is used for actual storing of data and another for storing priorities.

6. What is the data structures used to perform recursion?

Stack. Because of its LIFO (Last In First Out) property it remembers its 'caller' so knows whom to return when the function has to return. Recursion makes use of system stack for storing the return addresses of the function calls.

Every recursive function has its equivalent iterative (non-recursive) function. Even when such equivalent iterative procedures are written, explicit stack is to be used.

7. What are the notations used in Evaluation of Arithmetic Expressions using prefix and postfix forms?

Polish and Reverse Polish notations.

8. Convert the expression ((A + B) * C - (D - E) ^ (F + G)) to equivalent Prefix and Postfix notations.

Prefix Notation: ^ - * +ABC - DE + FG
Postfix Notation: AB + C * DE - - FG + ^

9. Sorting is not possible by using which of the following methods? (Insertion, Selection, Exchange, Deletion)

Sorting is not possible in Deletion. Using insertion we can perform insertion sort, using selection we can perform selection sort, using exchange we can perform the bubble sort (and other similar sorting methods). But no sorting method can be done just using deletion.

10. What are the methods available in storing sequential files ?

Straight merging,
Natural merging,
Polyphase sort,
Distribution of Initial runs.

11. List out few of the Application of tree data-structure?

The manipulation of Arithmetic expression,
Symbol Table construction,
Syntax analysis.

12. List out few of the applications that make use of Multilinked Structures?

Sparse matrix,
Index generation.

13. In tree construction which is the suitable efficient data structure? (Array, Linked list, Stack, Queue)

Linked list is the suitable efficient data structure.

14. What is the type of the algorithm used in solving the 8 Queens problem?

Backtracking.

15. In an AVL tree, at what condition the balancing is to be done?

If the 'pivotal value' (or the 'Height factor') is greater than 1 or less than -1.

16. What is the bucket size, when the overlapping and collision occur at same time?

One. If there is only one entry possible in the bucket, when the collision occurs, there is no way to accommodate the colliding value. This results in the overlapping of values.

17. Classify the Hashing Functions based on the various methods by which the key value is found.

Direct method,
Subtraction method,
Modulo-Division method,
Digit-Extraction method,
Mid-Square method,
Folding method,
Pseudo-random method.

18. What are the types of Collision Resolution Techniques and the methods used in each of the type?

Open addressing (closed hashing), The methods used include: Overflow block.
Closed addressing (open hashing), The methods used include: Linked list, Binary tree.

19. In RDBMS, what is the efficient data structure used in the internal storage representation?

B+ tree. Because in B+ tree, all the data is stored only in leaf nodes, that makes searching easier. This corresponds to the records that shall be stored in leaf nodes.

20. What is a spanning Tree?

A spanning tree is a tree associated with a network. All the nodes of the graph appear on the tree once. A minimum spanning tree is a spanning tree organized so that the total edge weight between nodes is minimized.

21. Does the minimum spanning tree of a graph give the shortest distance between any 2 specified nodes?

No. The Minimal spanning tree assures that the total weight of the tree is kept at its minimum. But it doesn't mean that the distance between any two nodes involved in the minimum-spanning tree is minimum.

22. Which is the simplest file structure? (Sequential, Indexed, Random)

Sequential is the simplest file structure.

23. Whether Linked List is linear or Non-linear data structure?

According to Access strategies Linked list is a linear one.
According to Storage Linked List is a Non-linear one.

2012-03-14T22:04:00.002-07:00

DBMS BASIC :-

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. What are the advantages of DBMS?

Redundancy is controlled.
Unauthorised access is restricted.
Providing multiple user interfaces.
Enforcing integrity constraints.
Providing backup and recovery.

5. What are the disadvantage in File Processing System?

Data redundancy and inconsistency.
Difficult in accessing data.
Data isolation.
Data integrity.
Concurrent access is not possible.
Security Problems.

6. Describe the three levels of data abstraction?

The are three levels of abstraction:

Physical level: The lowest level of abstraction describes how data are stored.
Logical level: The next higher level of abstraction, describes what data are stored in database and what relationship among those data.
View level: The highest level of abstraction describes only part of entire database.

7. Define the "integrity rules"?

There are two Integrity rules.

Entity Integrity: States that "Primary key cannot have NULL value"
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

Research Storage
System Relational Data System.

10. How is the data structure of System R different from the relational structure?

Unlike Relational systems in System R

Domains are not supported
Enforcement of candidate key uniqueness is optional
Enforcement of entity integrity is optional
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:

Physical Data Independence: Modification in physical level should not affect the logical level.
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.

28. What is DDL (Data Definition Language)?

A data base schema is specifies by a set of definitions expressed by a special language called DDL.

29. What is VDL (View Definition Language)?

It specifies user views and their mappings to the conceptual schema.

30. What is SDL (Storage Definition Language)?

This language is to specify the internal schema. This language may specify the mapping between two schemas.

31. 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.

32. What is DML (Data Manipulation Language)?

This language that enable user to access or manipulate data as organised by appropriate data model.

Procedural DML or Low level: DML requires a user to specify what data are needed and how to get those data.
Non-Procedural DML or High level: DML requires a user to specify what data are needed without specifying how to get those data.

33. What is DML Compiler?

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

34. What is Query evaluation engine?

It executes low-level instruction generated by compiler.

35. What is DDL Interpreter?

It interprets DDL statements and record them in tables containing metadata.

36. 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.

37. 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.

38. 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.

39. 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.

40. 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.

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2012-03-12T05:25:00.001-07:00

41. 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
(1).Minimizing redundancy, (2). Minimizing insertion, deletion and update anomalies.

42. 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.

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

X is a Super-key of R.
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.
1.) X is subset or equal to (or) XY = R.
2.) 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 1.) Ri = R for some i.
2.) 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:

Binary search style indexing
B-Tree indexing
Inverted list indexing
Memory resident table
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 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.

57. 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.

58. 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.

59. 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.

60. What are the different phases of transaction?

Different phases are
1.) Analysis phase,
2.) Redo Phase,
3.) Undo phase.

61. 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.

62. What is "transparent DBMS"?

It is one, which keeps its Physical Structure hidden from user.

63. 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.

64. 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.

Example: Select * From CUST Where '10/03/1990' IN (Select ODATE From ORDER Where CUST.CNUM = ORDER.CNUM)

65. What are the primitive operations common to all record management systems?

Addition, deletion and modification.

66. Name the buffer in which all the commands that are typed in are stored?

'Edit' Buffer.

67. What are the unary operations in Relational Algebra?

PROJECTION and SELECTION.

68. 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.

69. 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.

70. 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.

71. 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.

72. 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.

73. How do you communicate with an RDBMS?

You communicate with an RDBMS using Structured Query Language (SQL).

74. 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.

75. 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

1.) Database files
2.) Control files
3.) 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.

76. 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.

77. 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.

78. 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.

79. 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.

80. 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.

81. 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.

82. 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.

83. 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.

84. 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
1.) Implicit
2.) Explicit

85. What is cold backup and hot backup (in case of Oracle)?

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.
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.

86. 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.

87. What is a foreign key, and what is it used for?

A foreign key is used to establish relationships among relations in the relational model. Technically, a foreign key is a column (or columns) appearing in one relation that is (are) the primary key of another table. Although there may be exceptions, the values in the foreign key columns usually must correspond to values existing in the set of primary key values. This correspondence requirement is created in a database using a referential integrity constraint on the foreign key.

2012-03-11T10:42:00.000-07:00

Best HR Interview Question:-

Q1. Tell me about yourself.

Ans. Good morning,

Firstly I would like to thanks for giving me this oppurtunity and its my pleasure to introduce my self.

I am Pooja came from hyderabad. I did my Btech IT in JNTU H with 61%. I completed my intermediate with 78% from narayana junior college. And my schooling with 73%.

When it comes to family. My Family contain three member including me. My father and mother are Govt Employee's.

And then coming to my Hobbies. Playing shuttles and watching TV.

My strength is Each and every problem that occured in my life till now has taught me so much. And I think I am strong enough to face any situation in my life and career. My experience is my strength and I feel it as the best teacher.

Coming to My weakness is - I am too concerned with the people, which has given me so much pain and tears.

My Short term Goal is to join in this company and my Long Term goal is to I would like to be in a good position in your company and improving my skills and knowledge in the development of your organization and myself.

My Areas of interest are c, .Net.

I easily adapt to any kind of environment, and that helps me feel comfortable at work. Being calm and patient, helps me to solve the problems in a better way. And that is my biggest strength too.

Am very passionate to be a part of this company if I got selected I'll work whole hardly to the progress of the company.

Q2.Why should I hire you?

Ans. I am a quick learner, self confidence person and I am always Punctual. I think I will do my best and I will satisfy our company expectations.

Ans. As I'm a fresher I did not have any experience, but am very passionate to learn new skills, so that I can learn new things and prove my skills by applying new tools, and am a quik learner nd can grasp quickly, can handle any work with confidence and can reach the company expectations.

Ans. Im confident that I can cope with your expectation and along with your esteemed training & guidance it will be able for me to prove myself and I assure you that I will perform more then you expected if I get hired.

Q3. What are your strengths and weaknesses?

Ans. My strength is confident,i will never postpone my work,i can adopt my self in any environment.
My Weakness was i spent more time in a particular work until am satisfied.....
i was little bit emotional but i will express it in front of others.....

Ans. My strength- I have a leadership quality, and self confident, hard working.

My weakness-i spend more amount of time within a particular work because I am not satisfied until my work has done properly.

Q4. Why do you want to work at our company?

Ans. Sir everybody wants to work in best reputed companies. I feel that your one in that. So I feel that your company is a better platform for me to utilise my skills and ability to achieve organisational goals and learn new things.

Q5.what is the difference between hardwork and smartwork?

Ans. Hard work requires time and efforts....
Smart work reduces time and efforts....

Q6.How do feel about working about nights and weekend?

Ans. I will not work in nights and weekends because i want balance in my personal and professional life. but if some exceptional situation comes and company needs me at night or weekends i will be available there for company at any time.

Q7.What are your goals?

Ans. I want to reach the stage where In I'm respected & admired by the people.

Q8.What motivates you to do good jobs?

Ans. I am motivated when some one appreciates my more, and when I get some benefit and respect for my work, and by my dreams.

Q9.Give me a example of your creativity?

Ans. I think creativity is our imagination which we can make true.
I can show a positive side of anything. That's my creativity..

Q10. How long would you expect to work for us if hire?

Ans. I would like to work in your organization as much as long company needs my services to grow up the organization.

Q11.What are your career option right now?

Ans. My career options are to become an independent person and gain ability to face any adverse effects in life.And also to work hard and to put my complete efforts in bringing up the company to a top position

Q12. Would you lie for the company?

Ans. No, i would never lie.if i can lie at the very first step of my career,then i should have been a politician!

Q13. Tell me something about our company?

Ans. It is one of the reputed and fast growing company in IT Industry,It has a so many branches in India as well as throughout the world.This Company was founded in ______(year), The CEO of the Company is______(Name),This Company having the Project in Banking Sector,Govt Sector and So on.The growth rate of this company is_____(%)in the ______(year).these all i heared about this company.

Ans. I have got some information about this company through my friends, my friends told me if you want good future and you should join in this company,this company gives good communication skills and work punctuality and it will give vivacious personality to your also improve automatically if you do any mistakes your seniors should give suggestions... so you can go easily in this company...

Q14.How much salary do you expect?

Ans. Sir, I'm expecting the salary as per the company norms as well as my qualification.

Q15. Do you have any question for me?

Ans. Thank you sir for giving me this opportunity. I always want improvements in myself, though I have tried to give my best to you, but would you like to suggest some areas where I need to improve more.

Ans. Thank you very much for giving me this opportunity. I tried to answer to the best I could, but still if you can give me feedback on the same which will help me inching towards perfection.

2012-03-11T10:21:00.000-07:00

SQL Server Question:-

1. What is RDBMS?

Relational Data Base Management Systems (RDBMS) are database management systems that maintain data records and indices in tables. Relationships may be created and maintained across and among the data and tables. In a relational database, relationships between data items are expressed by means of tables. Interdependencies among these tables are expressed by data values rather than by pointers. This allows a high degree of data independence. An RDBMS has the capability to recombine the data items from different files, providing powerful tools for data usage.

2. What are the properties of the Relational tables?

tables have six properties:

Values are atomic.
Column values are of the same kind.
Each row is unique.
The sequence of columns is insignificant.
The sequence of rows is insignificant.
Each column must have a unique name.

3. What is Normalization?

Database normalization is a data design and organization process applied to data structures based on rules that help building relational databases. In relational database design, the process of organizing data to minimize redundancy is called normalization. Normalization usually involves dividing a database into two or more tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships.

4. What is De-normalization?

De-normalization is the process of attempting to optimize the performance of a database by adding redundant data. It is sometimes necessary because current DBMSs implement the relational model poorly. A true relational DBMS would allow for a fully normalized database at the logical level, while providing physical storage of data that is tuned for high performance. De-normalization is a technique to move from higher to lower normal forms of database modeling in order to speed up database access.

5. What are different normalization forms?

1NF: Eliminate Repeating Groups Make a separate table for each set of related attributes, and give each table a primary key. Each field contains at most one value from its attribute domain.
2NF: Eliminate Redundant Data If an attribute depends on only part of a multi-valued key, remove it to a separate table.
3NF: Eliminate Columns Not Dependent On Key If attributes do not contribute to a description of the key, remove them to a separate table. All attributes must be directly dependent on the primary key.
BCNF: Boyce-Codd Normal Form If there are non-trivial dependencies between candidate key attributes, separate them out into distinct tables.
4NF: Isolate Independent Multiple Relationships No table may contain two or more 1:n or n:m relationships that are not directly related.
5NF: Isolate Semantically Related Multiple Relationships There may be practical constrains on information that justify separating logically related many-to-many relationships.
ONF: Optimal Normal Form A model limited to only simple (elemental) facts, as expressed in Object Role Model notation.
DKNF: Domain-Key Normal Form A model free from all modification anomalies is said to be in DKNF.

Remember, these normalization guidelines are cumulative. For a database to be in 3NF, it must first fulfill all the criteria of a 2NF and 1NF database.

7. What is Trigger?

A trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE or UPDATE) occurs. Triggers are stored in and managed by the DBMS. Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion. A trigger cannot be called or executed; DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is stored at the database level. Stored procedures, however, are not event-drive and are not attached to a specific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to the procedure while triggers are implicitly executed. In addition, triggers can also execute stored procedures.

8. What is Nested Trigger?

A trigger can also contain INSERT, UPDATE and DELETE logic within itself, so when the trigger is fired because of data modification it can also cause another data modification, thereby firing another trigger. A trigger that contains data modification logic within itself is called a nested trigger.

9. What is View?

A simple view can be thought of as a subset of a table. It can be used for retrieving data, as well as updating or deleting rows. Rows updated or deleted in the view are updated or deleted in the table the view was created with. It should also be noted that as data in the original table changes, so does data in the view, as views are the way to look at part of the original table. The results of using a view are not permanently stored in the database. The data accessed through a view is actually constructed using standard T-SQL select command and can come from one to many different base tables or even other views.

10. What is Index?

An index is a physical structure containing pointers to the data. Indices are created in an existing table to locate rows more quickly and efficiently. It is possible to create an index on one or more columns of a table, and each index is given a name. The users cannot see the indexes; they are just used to speed up queries. Effective indexes are one of the best ways to improve performance in a database application. A table scan happens when there is no index available to help a query. In a table scan SQL Server examines every row in the table to satisfy the query results. Table scans are sometimes unavoidable, but on large tables, scans have a terrific impact on performance.

11. What is a Linked Server?

Linked Servers is a concept in SQL Server by which we can add other SQL Server to a Group and query both the SQL Server dbs using T-SQL Statements. With a linked server, you can create very clean, easy to follow, SQL statements that allow remote data to be retrieved, joined and combined with local data. Stored Procedure sp_addlinkedserver, sp_addlinkedsrvlogin will be used add new Linked Server.

12. What is Cursor?

Cursor is a database object used by applications to manipulate data in a set on a row-by- row basis, instead of the typical SQL commands that operate on all the rows in the set at one time.

In order to work with a cursor we need to perform some steps in the following order:

Declare cursor
Open cursor
Fetch row from the cursor
Process fetched row
Close cursor
Deallocate cursor

13. What is Collation?

Collation refers to a set of rules that determine how data is sorted and compared. Character data is sorted using rules that define the correct character sequence, with options for specifying case sensitivity, accent marks, kana character types and character width.

14. What is Difference between Function and Stored Procedure?

UDF can be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section where as Stored procedures cannot be. UDFs that return tables can be treated as another rowset. This can be used in JOINs with other tables. Inline UDF's can be thought of as views that take parameters and can be used in JOINs and other Rowset operations.

15. What is sub-query? Explain properties of sub-query?

Sub-queries are often referred to as sub-selects, as they allow a SELECT statement to be executed arbitrarily within the body of another SQL statement. A sub-query is executed by enclosing it in a set of parentheses. Sub-queries are generally used to return a single row as an atomic value, though they may be used to compare values against multiple rows with the IN keyword.

A subquery is a SELECT statement that is nested within another T-SQL statement. A subquery SELECT statement if executed independently of the T-SQL statement, in which it is nested, will return a resultset. Meaning a subquery SELECT statement can standalone and is not depended on the statement in which it is nested. A subquery SELECT statement can return any number of values, and can be found in, the column list of a SELECT statement, a FROM, GROUP BY, HAVING, and/or ORDER BY clauses of a T-SQL statement. A Subquery can also be used as a parameter to a function call. Basically a subquery can be used anywhere an expression can be used.

16. What are different Types of Join?

Cross Join A cross join that does not have a WHERE clause produces the Cartesian product of the tables involved in the join. The size of a Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table. The common example is when company wants to combine each product with a pricing table to analyze each product at each price.
Inner Join A join that displays only the rows that have a match in both joined tables is known as inner Join. This is the default type of join in the Query and View Designer.
Outer Join A join that includes rows even if they do not have related rows in the joined table is an Outer Join. You can create three different outer join to specify the unmatched rows to be included:

Left Outer Join: In Left Outer Join all rows in the first-named table i.e. "left" table, which appears leftmost in the JOIN clause are included. Unmatched rows in the right table do not appear.
Right Outer Join: In Right Outer Join all rows in the second-named table i.e. "right" table, which appears rightmost in the JOIN clause are included. Unmatched rows in the left table are not included.
Full Outer Join: In Full Outer Join all rows in all joined tables are included, whether they are matched or not.

Self Join This is a particular case when one table joins to itself, with one or two aliases to avoid confusion. A self join can be of any type, as long as the joined tables are the same. A self join is rather unique in that it involves a relationship with only one table. The common example is when company has a hierarchal reporting structure whereby one member of staff reports to another. Self Join can be Outer Join or Inner Join.

17. What are primary keys and foreign keys?

Primary keys are the unique identifiers for each row. They must contain unique values and cannot be null. Due to their importance in relational databases, Primary keys are the most fundamental of all keys and constraints. A table can have only one Primary key. Foreign keys are both a method of ensuring data integrity and a manifestation of the relationship between tables.

18. What is User Defined Functions? What kind of User-Defined Functions can be created?

User-Defined Functions allow defining its own T-SQL functions that can accept 0 or more parameters and return a single scalar data value or a table data type.
Different Kinds of User-Defined Functions created are:

Scalar User-Defined Function A Scalar user-defined function returns one of the scalar data types. Text, ntext, image and timestamp data types are not supported. These are the type of user-defined functions that most developers are used to in other programming languages. You pass in 0 to many parameters and you get a return value.
Inline Table-Value User-Defined Function An Inline Table-Value user-defined function returns a table data type and is an exceptional alternative to a view as the user-defined function can pass parameters into a T-SQL select command and in essence provide us with a parameterized, non-updateable view of the underlying tables.
Multi-statement Table-Value User-Defined Function A Multi-Statement Table-Value user-defined function returns a table and is also an exceptional alternative to a view as the function can support multiple T-SQL statements to build the final result where the view is limited to a single SELECT statement. Also, the ability to pass parameters into a TSQL select command or a group of them gives us the capability to in essence create a parameterized, non-updateable view of the data in the underlying tables. Within the create function command you must define the table structure that is being returned. After creating this type of user-defined function, It can be used in the FROM clause of a T-SQL command unlike the behavior found when using a stored procedure which can also return record sets.

19. What is Identity?

Identity (or AutoNumber) is a column that automatically generates numeric values. A start and increment value can be set, but most DBA leave these at 1. A GUID column also generates numbers; the value of this cannot be controlled. Identity/GUID columns do not need to be indexed.

20. What is DataWarehousing?

Subject-oriented, meaning that the data in the database is organized so that all the data elements relating to the same real-world event or object are linked together;
Time-variant, meaning that the changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time;
Non-volatile, meaning that data in the database is never over-written or deleted, once committed, the data is static, read-only, but retained for future reporting.
Integrated, meaning that the database contains data from most or all of an organization's operational applications, and that this data is made consistent.

21. What's the difference between a primary key and a unique key?

Both primary key and unique key enforces uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where are unique creates a nonclustered index by default. Another major difference is that, primary key doesn't allow NULLs, but unique key allows one NULL only.

22. What is difference between DELETE and TRUNCATE commands?

Delete command removes the rows from a table based on the condition that we provide with a WHERE clause. Truncate will actually remove all the rows from a table and there will be no data in the table after we run the truncate command.

TRUNCATE:

TRUNCATE is faster and uses fewer system and transaction log resources than DELETE.
TRUNCATE removes the data by deallocating the data pages used to store the table's data, and only the page deallocations are recorded in the transaction log.
TRUNCATE removes all rows from a table, but the table structure, its columns, constraints, indexes and so on, remains. The counter used by an identity for new rows is reset to the seed for the column.
You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint. Because TRUNCATE TABLE is not logged, it cannot activate a trigger.
TRUNCATE cannot be rolled back.
TRUNCATE is DDL Command.
TRUNCATE Resets identity of the table

DELETE:

DELETE removes rows one at a time and records an entry in the transaction log for each deleted row.
If you want to retain the identity counter, use DELETE instead. If you want to remove table definition and its data, use the DROP TABLE statement.
DELETE Can be used with or without a WHERE clause
DELETE Activates Triggers.
DELETE can be rolled back.
DELETE is DML Command.
DELETE does not reset identity of the table.

23. What is the difference between a Local and a Global temporary table?

A local temporary table exists only for the duration of a connection or, if defined inside a compound statement, for the duration of the compound statement.
A global temporary table remains in the database permanently, but the rows exist only within a given connection. When connection is closed, the data in the global temporary table disappears. However, the table definition remains with the database for access when database is opened next time.

24. What is UNIQUE KEY constraint?

A UNIQUE constraint enforces the uniqueness of the values in a set of columns, so no duplicate values are entered. The unique key constraints are used to enforce entity integrity as the primary key constraints.

25. What is FOREIGN KEY?

A FOREIGN KEY constraint prevents any actions that would destroy links between tables with the corresponding data values. A foreign key in one table points to a primary key in another table. Foreign keys prevent actions that would leave rows with foreign key values when there are no primary keys with that value. The foreign key constraints are used to enforce referential integrity.

26. What is CHECK Constraint?

A CHECK constraint is used to limit the values that can be placed in a column. The check constraints are used to enforce domain integrity.

27. What is NOT NULL Constraint?

A NOT NULL constraint enforces that the column will not accept null values. The not null constraints are used to enforce domain integrity, as the check constraints.

28. What is candidate key ?

A candidate key is one that can identify each row of a table uniquely. Generally a candidate key becomes the primary key of the table. If the table has more than one candidate key, one of them will become the primary key, and the rest are called alternate keys.

SHORTCUT-TIP AND TRICK-IMPORTANT LINKS

Q1. Tell me about yourself.

Q3. What are your strengths and weaknesses?

Ans. My strength is confident,i will never postpone my work,i can adopt my self in any environment. My Weakness was i spent more time in a particular work until am satisfied..... i was little bit emotional but i will express it in front of others.....

Q4. Why do you want to work at our company?

Ans. My strength is confident,i will never postpone my work,i can adopt my self in any environment.
My Weakness was i spent more time in a particular work until am satisfied.....
i was little bit emotional but i will express it in front of others.....