What is a Microsoft Intermediate Language?

Intermediate Language. Also known as MSIL (Microsoft Intermediate Language) or CIL (Common Intermediate Language). All .NET source code (of any language) is compiled to MSIL.

When compiling the source code to managed code, the compiler translates the source into Microsoft intermediate language (MSIL). This is a CPU-independent set of instructions that can efficiently be converted to native code. Microsoft intermediate language (MSIL) is a translation used as the output of a number of compilers. It is the input to a just-in-time (JIT) compiler. The Common Language Runtime includes a JIT compiler for the conversion of MSIL to native code.

Before Microsoft Intermediate Language (MSIL) can be executed it, must be converted by the .NET Framework just-in-time (JIT) compiler to native code. This is CPU-specific code that runs on the same computer architecture as the JIT compiler. Rather than using time and memory to convert all of the MSIL in a portable executable (PE) file to native code. It converts the MSIL as needed whilst executing, then caches the resulting native code so its accessible for any subsequent calls.

Collection Class

Que:- What�s the .NET datatype that allows the retrieval of data by a unique key?
Ans:- HashTable.

What does the "EnableViewState" property do?

It allows the page to save the users input on a form across postbacks.  It
saves the server-side values for a given control into ViewState, which
is stored as a hidden value on the page before sending the page to the
clients browser.  When the page is posted back to the server the server
control is recreated with the state stored in viewstate.

What is MSIL, ??

MSILis the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL. 

 MSIL also allows the .NET Framework to JIT compile the assembly on the installed computer.

What�s a bubbled event?

  When you have a complexcontrol, like DataGrid, writing an event processing routine for each
object (cell, button, row, etc.) is quite tedious. The controls can   bubble up their eventhandlers, allowing the main DataGrid event handler  to take care of its constituents.

Where do you store the information about the user�s locale?

System.Web.UI.Page.Culture
 

What is Static Method?

Methods that you can call directly without first creating an instance of a class. Eg: Main() Method, Console.WriteLine()
You can use static fields, methods, properties and even constructors which will be called before any instance of the class is created
 As static methods may be called without any reference to object, you can not use instance members inside static methods or properties, while you may call a static member from a non-static context. The reason for being able to call static members from non-static context is that static members belong to the class and are present irrespective of the existence of even a single object

Static Constructor

In C# it is possible to write a static no-parameter constructor for a class. Such a class is executed once, when first object of class is created.
One reason for writing a static constructor would be if your class has some static fields or properties that need to be initialized from an external source before the class is first used.
Eg:
Class MyClass
{
static MyClass()
{
//Initialization Code for static fields and properties.
}
}

Basic OOPS Concepts

Class
A user-defined data structure that groups properties and methods. Class doesn�t occupies memory.

Object
Instance of Class is called object. An object is created in memory using keyword �new�.


Encapsulation
Wrapping up of data and function into a single unit is known as Encapsulation.

Properties
Attribute of object is called properties. Eg1:- A car has color as property.
Eg2:
private string m_Color;;
public string Color
{
get
{
return m_Color;
}
set
{
m_Color = value;
}
}

Car Maruti = new Car();
Maruti.Color= �White�;
Console.Write(Maruti.Color);

Difference between Struct and Class

 Struct are Value type and are stored on stack, while Class are Reference type and are stored on heap.
 Struct �do not support� inheritance, while class supports inheritance.
 Struct should be used when you want to use a small data structure, while Class is better choice for complex data structure.

Garbage Collection

 Garbage collection is the mechanism that reclaims the memory resources of an object when it is no longer referenced by a variable.
.Net Runtime performs automatically performs garbage collection, however you can force the garbage collection to run at a certain point in your code by calling System.GC.Collect().
 Advantage of Garbage collection : It prevents programming error that could otherwise occur by incorrectly deleting or failing to delete objects

What is meant by state management?

State Management is a technique used to maintain the state of between HTTP Request and Response.

There are two ways one can maintain state.

1) Client Side State Management: It includes Cookies, Query String, Hidden Field, View State, Control State, HttpContext.Current.Item

2) Server Side State Management: It Includes Application Object, Cache Object, Session State, Profile Properties

What is Reflection? and Uses

Reflection is ability to read metadata at runtime
Uses Of Reflection
1. Viewing Metadata.
2.Performing type discovery.
3.Late binding to methods and properties (dynamic invocation)
4.Creating new types at runtime(Reflection EMIT)

1) Load assemblies dynamically
2) Invoke methods at runtime
3) Retriving type information at runtime.

What is Web Control

Webcontrol is the base class that define methods properties events for all the controls in System.Web.UI.Webcontrols namespace.

A control is an object that can be drawn on to the Web Form to enable or enhance user interaction with the application. Examples of these controls include the TextBoxes Buttons Labels Radio Buttons etc. All these Web server controls are based on the System.Web.UI.Control class

ASP .Net Page Life Cycle

1. Page Request

2. Start

3. Page Initialization

4. Load

5. Validation

6. Postback and event Handling

7. Rendering

8. Unload

For The Page Execution Life Cycle Just Remember SILVER.
S-Start

I-Page Initialization

L-Load

V-Validation

E-Postback event handling

R-Rendering



Page Preinit
This will be executed before memory initialization for web page [before
constructing web page]

Attaching theme master page dynamically to webpage is possible using preinit
event proc

Page init
This will be executed when memory is initialized for webpage

Page load
This will be executed when submitted data and controls are loaded

Database connectivity reading submitted data can be placed within pageload

PagePrerender
This will be executed before rendering html content from server side control

Control behaviour can be changed b4 producing client side control

Page Unload
This will be executed once memory is released for webpage

Authentication in .Net

Windows authentication enables you to identify users without creating a custom page. Credentials are stored in the Web server s local user database or an Active Directory domain. Once identified you can use the user s credentials to gain access to resources that are protected by Windows authorization.

Forms authentication enables you to identify users with a custom database such as an ASP.NET membership database. Alternatively you can implement your own custom database. Once authenticated you can reference the roles the user is in to restrict access to portions of your Web site.

Passport authentication relies on a centralized service provided by Microsoft. Passport authentication identifies a user with using his or her e-mail address and a password and a single Passport account can be used with many different Web sites. Passport authentication is primarily used for public Web sites with thousands of users.

Anonymous authentication does not require the user to provide credentials.

What is Web.con fig ?

Web.con fig file is a collection of settings.
like
database.
session state.
error handling
security.
if u want to do any change we can perform here so it reflect to entire project.

Example:
we develop a project for a company, that company shifted a new place so address is changed. In this time what we do simply changes in web.config file.

Difference between ViewState and Session

ViewState persist the values of controls of particular page in the client (browser) when post back operation done. When user requests another page previous page data no longer available.

SessionState persist the data of particular user in the server. This data available till user close the browser or session time completes.

View state & Session state are objects which are used for maintaining a state.

.View state maintains a state in a single page.if we go to another page the state will be lossed.

. Session state we can maintain a state as long as browser opened or session time expired.

What is an Use Case?

A use case specifies the behavior of a system or a part of a system, óse cases are used to capture the behavior that need to be developed. It involves the interaction of actors and the system

What is Architecture?

Architecture is not only taking care of the structural and behavioral aspect of a software system but also taking into account the software usage, functionality, performance, reuse, economic and technology constraints.

What is SDLC?

SDLC is Software Development Life Cycle. SDLC of a system included processes that are Use case driven, Architecture centric and Iterative and Incremental. This Life cycle is divided into phases. Phase is a time span between two milestones. The milestones are Inception, Elaboration, Construction, and Transition. Process Workflows that evolve through these phase are Business Modeling, Requirement gathering, Analysis and Design, Implementation, Testing, Deployment. Supporting Workflows are Configuration and change management, Project management.

What are Relationships?

There are different kinds of relationships: Dependencies, Generalization, and Association. Dependencies are relations ships between two entities that that a change in specification of one thing may affect another thing. Most commonly it is used to show that one class uses another class as an argument in the signature of the operation. Generalization is relationships specified in the class subclass scenario, it is shown when one entity inherits from other. Associations are structural relationships that are: a room has walls, Person works for a company. Aggregation is a type of association where there is a has a relation ship, That is a room has walls, ño if there are two classes room and walls then the relation ship is called a association and further defined as an aggregation.

How are the diagrams divided?

The nine diagrams are divided into static diagrams and dynamic diagrams.
Static Diagrams (Also called Structural Diagram): Class diagram, Object diagram, Component Diagram, Deployment diagram.
Dynamic Diagrams (Also called Behavioral Diagrams): Use Case Diagram, Sequence Diagram, Collaboration Diagram, Activity diagram, Statechart diagram.

Types of Modeling Diagram

Modeling diagrams that are commonly used are, there are 9 of them.
 Use case diagram,
Class Diagram,
Object Diagram,
Sequence Diagram,
Statechart Diagram,
Collaboration Diagram,
Activity Diagram,
Component diagram,
Deployment Diagram.

What is modeling? What are the advantages of creating a model?

Modeling is a proven and well-accepted engineering technique which helps build a model.
Model is a simplification of reality; it is a blueprint of the actual system that needs to be built.
Model helps to visualize the system.
Model helps to specify the structural and behavior of the system.
Model helps make templates for constructing the system. Model helps document the system.

What are the major three types of modeling used?

Major three types of modeling are
structural,
behavioral,
architectural.

Index Types

Clustered Index:- A Clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table may have only one clustered index.

Non-Clustered Index:- A Non-Clustered index is a special type of index in which the logical order of the index does not match the physical stored order of the rows in the disk. The leaf nodes of a non-clustered index does not consists of the data pages. instead the leaf node contains index rows.

Whats is integrity constraint

An integrity constraint allows the definition of certain restrictions, at the table level, on the data that is entered into a table.

What is Dead LOck ?

Deadlock is a unique situation in a multi user system that causes two or more users to wait indefinitely for a locked resource. First user needs a resource locked by the second user and the second user needs a resource locked by the first user. To avoid dead locks, avoid using exclusive table lock and if using, use it in the same sequence and use Commit frequently to release locks.

What is a "constraint"?

- A constraint allows you to apply simple referential integrity checks to a table. There are four primary types of constraints that are currently supported by SQL Server:

PRIMARY/UNIQUE - enforces uniqueness of a particular table column.

DEFAULT - specifies a default value for a column in case an insert operation does not provide one.

 FOREIGN KEY - validates that every value in a column exists in a column of another table.

 CHECK - checks that every value stored in a column is in some specified list.

 Each type of constraint performs a specific type of action. Default is not a constraint. NOT NULL is one more constraint which does not allow values in the specific column to be null. And also it the only constraint which is not a table level constraint.

What is a "functional dependency

Functional dependency relates to how one object depends upon the other in the database. for example, procedure/function sp2 may be called by procedure sp1. Then we say that sp1 has functional dependency on sp2.

Difference Between Union and Union All

1.Union will remove the duplicate rows from the result set while

2. Union wont allow the duplicates,where as unionall allows the duplicates.
 3.Union all does'nt remove rows from the result

4.Union is callback , union all doesnt call back

What is DDL DML ?

Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:

CREATE - to create objects in the database
ALTER - alters the structure of the database
DROP - delete objects from the database
TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
COMMENT - add comments to the data dictionary
RENAME - rename an object



DML

Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:

SELECT - retrieve data from the a database
INSERT - insert data into a table
UPDATE - updates existing data within a table
DELETE - deletes all records from a table, the space for the records remain
MERGE - UPSERT operation (insert or update)
CALL - call a PL/SQL or Java subprogram
EXPLAIN PLAN - explain access path to data
LOCK TABLE - control concurrency

What is a SQL view?

- An output of a query can be stored as a view. View acts like small table which meets our criterion. View is a precomplied SQL query which is used to select data from one or more tables. A view is like a table but it doesn�t physically take any space. View is a good way to present data in a particular format if you use that query quite often. View can also be used to restrict users from accessing the tables directly.

What�s an Assembly?

Assemblies are the building blocks of .NET Framework applications; they form the fundamental unit of deployment, version control, reuse, activation scoping, and security permissions. An assembly is a collection of types and resources that are built to work together and form a logical unit of functionality. An assembly provides the common language runtime with the information it needs to be aware of type implementations. To the runtime, a type does not exist outside the context of an assembly.

What is Delay Signing?

Delay signing allows you to place a shared assembly in the GAC by signing the assembly with just the public key. This allows the assembly to be signed with the private key at a later stage, when the development process is complete and the component or assembly is ready to be deployed. This process enables developers to work with shared assemblies as if they were strongly named, and it secures the private key of the signature from being accessed at different stages of development.

What�s a strong name?

A strong name includes the name of the assembly, version number, culture identity, and a public key token.

Where are shared assemblies stored?

Shared assemblies stored  in Global assembly cache.

.What is Method overloading? and Overriding

Method Overriding

Use the override modifier to modify a method, a property, an indexer, or an event.

An override method provides a new implementation of a member inherited from a base class.
The method overridden by an override declaration is known as the overridden base method.
The overridden base method must have the same signature as the override method.
You cannot override a non-virtual or static method. The overridden base method must be virtual, abstract, or override.

Method overloading occurs when a class contains two methods with the same name, but different signatures. or  same Funtion  name different paramaters

Difference between String.Empty vs null?

String.Empty:

• Represents the empty string. This field is read-only.
• The value of this field is the zero-length string, ��.
• In application code, this field is most commonly used in assignments to initialize a string variable to an empty string. To test whether the value of a string is String.Empty, use the IsNullOrEmpty method.

Null:

• The null keyword is a literal that represents a null reference, one that does not refer to any object. null is the default value of reference-type variables.
• C# 2.0 introduces nullable types, which are data types that may be set to an undefined value.

What is Constructors?

Constructors is a special Member Function intialize the object of the classs.
Static classes and structs can also have constructors.
Whenever a class or struct is created, its constructor is called.
A class or struct may have multiple constructors that take different arguments.

Constructors enable the programmer to set default values, limit instantiation, and write code that is flexible and easy to read.


Constructor
A constructor is a special method whose task is to initialize the object of its class
 It is special because its name is the same as the class name.
 They do not have return types, not even void and therefore they cannot return values
They cannot be inherited, though a derived class can call the base class constructor.
Constructor is invoked whenever an object of its associated class is created.
Note: There is always atleast one constructor in every class.
If you do not write a constructor, C# automatically provides one for you, this is called default constructor. Eg: class A, default constructor is A().

Static Members of the class
Static members belong to the whole class rather than to individual object
Static members are accessed with the name of class rather than reference to objects.
Eg:
class Test
{
public int rollNo;
public int mathsMarks;
public static int totalMathMarks;
}

class TestDemo
{
public static void main()
{
Test stud1 = new Test();
stud1.rollNo = 1;
stud1.mathsMarks = 40;

stud2.rollNo = 2;
stud2.mathsMarks = 43;

Test.totalMathsMarks = stud1.mathsMarks + stud2.mathsMarks;
}
}

. What is Structs keyword?

Structs are defined by using the struct keyword.

• A struct may not declare a default constructor (a constructor without parameters) or a destructor.
• Structs are copied on assignment. When a struct is assigned to a new variable, all the data is copied, and any modification to the new copy does not change the data for the original copy. This is important to remember when working with collections of value types such as Dictionary<string, myStruct>.
• Structs are value types and classes are reference types.
• Unlike classes, structs can be instantiated without using a new operator.
• Structs can declare constructors that have parameters.
• A struct cannot inherit from another struct or class, and it cannot be the base of a class. All structs inherit directly from System.ValueType, which inherits from System.Object.
• A struct can implement interfaces.
• A struct can be used as a nullable type and can be assigned a null value.

What is Dictionary Generic Class?

Represents a collection of keys and values.
The Dictionary generic class provides a mapping from a set of keys to a set of values. Each addition to the dictionary consists of a value and its associated key. Retrieving a value by using its key is very fast, close to O(1), because the Dictionary class is implemented as a hash table.
The capacity of a Dictionary is the number of elements the Dictionary can hold. As elements are added to a Dictionary, the capacity is automatically increased as required by reallocating the internal array.

Difference between Hashtable vs Dictionary?

• The Hashtable class and the Dictionary generic class implement the IDictionary interface. The Dictionary generic class also implements the IDictionary generic interface. Therefore, each element in these collections is a key-and-value pair.
• A Hashtable object consists of buckets that contain the elements of the collection. A bucket is a virtual subgroup of elements within the Hashtable, which makes searching and retrieving easier and faster than in most collections. Each bucket is associated with a hash code, generated using a hash function and based on the key of the element.
• When an object is added to a Hashtable, it is stored in the bucket that is associated with the hash code that matches the object�s hash code. When a value is being searched for in the Hashtable, the hash code is generated for that value, and the bucket associated with that hash code is searched.
• The Dictionary class has the same functionality as the Hashtable class. A Dictionary of a specific type (other than Object) has better performance than a Hashtable for value types because the elements of Hashtable are of type Object and, therefore, boxing and unboxing typically occur if storing or retrieving a value type.

What is Hashtable Class?

Represents a collection of key/value pairs that are organized based on the hash code of the key.
Each element is a key/value pair stored in a DictionaryEntry object. A key cannot be a null reference (Nothing in Visual Basic), but a value can be. Key objects must be immutable as long as they are used as keys in the Hashtable.

What is LINQ?

Enables the use of Language-Integrated Query (LINQ) in an ASP.NET Web page through markup text to retrieve and modify data from a data object.

• Language-Integrated Query (LINQ) is a query syntax that defines a set of query operators that enable traversal, filter, and projection operations to be expressed in a declarative way in any .NET-based programming language. The data object can be an in-memory data collection or an object that represents data from a database. You can retrieve or modify the data without having to write SQL commands for each operation.
• The LinqDataSource control enables you to use LINQ in an ASP.NET Web page by setting properties in markup text. The LinqDataSource control uses LINQ to SQL to automatically generate the data commands.

What type of Operation we can do in C# using LINQ?

The LinqDataSource control applies data operations in the following order:

• Where (specify which data records to return).
• Order By (sort).
• Group By (aggregate data records that share values).
• Order Groups By (sort grouped data).
• Select (specify which fields or properties to return).
• Auto-sort (sort data records by a property that the user has selected).
• Auto-page (retrieve a subset of data records that were selected by the user).

. What is LinkedList?

LinkedList<T> is a general-purpose linked list. It supports enumerators and implements the ICollection interface, consistent with other collection classes in the .NET Framework.

• LinkedList<T> provides separate nodes of type LinkedListNode<T>, so insertion and removal are O (1) operations.
• You can remove nodes and reinsert them, either in the same list or in another list, which results in no additional objects allocated on the heap. Because the list also maintains an internal count, getting the Count property is an O (1) operation.
• Each node in a LinkedList<T> object is of the type LinkedListNode<T>. Because the LinkedList<T> is doubly linked, each node points forward to the Next node and backward to the previous node. Lists that contain reference types perform better when a node and its value are created at the same time. LinkedList<T> accepts null as a valid Value property for reference types and allows duplicate values.
• If the LinkedList<T> is empty, the First and Last properties contain null.
• The LinkedList<T> class does not support chaining, splitting, cycles, or other features that can leave the list in an inconsistent state. The list remains consistent on a single thread. The only multithreaded scenario supported by LinkedList<T> is multithreaded read operations.

What is Interface?

• An interface is like an abstract base class: any non-abstract type that implements the interface must implement all its members.
• An interface cannot be instantiated directly.
• Interfaces can contain events, indexers, methods, and properties.
• Interfaces contain no implementation of methods.
• Classes and structs can implement more than one interface.
• An interface itself can inherit from multiple interfaces.

. What is polymorphism?

Through inheritance, a class can be used as more than one type; it can be used as its own type, any base types, or any interface type if it implements interfaces. This is called polymorphism.

What is Generics in C#?

Generics are a new feature in version 2.0 of the C# language and the common language runtime (CLR). Generics introduce to the .NET Framework the concept of type parameters.

• Use generic types to maximize code reuse, type safety, and performance.
• The most common use of generics is to create collection classes.
• The .NET Framework class library contains several new generic collection classes in the System.Collections.Generic namespace. These should be used whenever possible in place of classes such as ArrayList in the System.Collections namespace.
• You can create your own generic interfaces, classes, methods, events and delegates.
• Generic classes may be constrained to enable access to methods on particular data types.
• Information on the types used in a generic data type may be obtained at run-time by means of reflection.

.What is Abstract Class?

The abstract keyword enables you to create classes and class members that are incomplete and must be implemented in a derived class.

• An abstract class cannot be instantiated. The purpose of an abstract class is to provide a common definition of a base class that multiple derived classes can share.
• Abstract classes may also define abstract methods. This is accomplished by adding the keyword abstract before the return type of the method.
• Abstract methods have no implementation
• Derived classes of the abstract class must implement all abstract methods. When an abstract class inherits a virtual method from a base class, the abstract class can override the virtual method with an abstract method.
• An abstract class must provide implementation for all interface members.
• An abstract class that implements an interface might map the interface methods onto abstract methods.
• A non-abstract class derived from an abstract class must include actual implementations of all inherited abstract methods and accessors.

What is Sealed Class?

The sealed keyword enables you to prevent the inheritance of a class or certain class members that were previously marked virtual.
A sealed class cannot be used as a base class. For this reason, it cannot also be an abstract class. Sealed classes prevent derivation. Because they can never be used as a base class, some run-time optimizations can make calling sealed class members slightly faster.

What is Sealed Class?

The sealed keyword enables you to prevent the inheritance of a class or certain class members that were previously marked virtual.
A sealed class cannot be used as a base class. For this reason, it cannot also be an abstract class. Sealed classes prevent derivation. Because they can never be used as a base class, some run-time optimizations can make calling sealed class members slightly faster.

1. What is Partial Class?

It is possible to split the definition of a class or a struct, or an interface over two or more source files. Each source file contains a section of the class definition, and all parts are combined when the application is compiled. There are several situations when splitting a class definition is desirable:

• When working on large projects, spreading a class over separate files allows multiple programmers to work on it simultaneously.
• When working with automatically generated source, code can be added to the class without having to recreate the source file. Visual Studio uses this approach when creating Windows Forms, Web Service wrapper code, and so on. You can create code that uses these classes without having to edit the file created by Visual Studio.
• To split a class definition, use the partial keyword modifier

What is the Lazy Design Pattern?

The approach of the Lazy Design Pattern is not to create objects until a specific requirement matches, and when it matches, objectcreation is triggered.

 

 A simple example of this pattern is a Job Portal application. Say you register yourself in that site thus filling up the registration table, only when the registration table is filled, the otherobjects are created and invoked, that prompt you to fill in other details too, which will be saved in other tables.

 

Describe the Builder Design Pattern

In a builder design pattern, an object creation process is separated from the object design construct.

This is useful becuase thesame method that deals with construction of the object, can be used to construct different design constructs.

What are Creational Design Patterns?

The Creational Design Patterns focus on how objects are created and utilized in an application. They tackle the aspects of when andhow objects are created, keeping in mind whats the best way these objects should be created

Listed below are some of the commonly known Creational Design Patterns:<br />

>>> Abstract Factory Pattern

>>> Factory Pattern

>>> Builder Pattern

>>> Lazy Pattern

>>> Prototype Pattern

>>> Singleton Pattern

Types of Design Pattern

Design Patterns are categorized into 3 types:

Design Patterns are categorized into 3 types:

 

1. Creational Patterns

 

  2. Structural Patterns

 

 3. Behavioral Patterns

What is Design Pattern .Net Framework

Design Pattern   is a re-usable, high quality solution to a given requirement, task or recurring problem. Further, it does not comprise of a complete solution that may be instantly converted to a code component, rather it provides a framework for how to solve a problem.

In 1994, the release of the book Design Patterns, Elements of Reusable Object Oriented Software made design patternspopular .Because design patterns consist of proven reusable architectural concepts, they are reliable and they speed up softwaredevelopment process

 

Design Patterns are in a continious phase of evolution, which means that they keep on getting better  & better as they aretested against time, reliability and subjected to continious improvements. Further, design patterns have evolved towardstargeting specific domains. For example, windows-based banking applications are usually based on singleton patterns, e-commerce web applications are based on the MVC (Model-View-Controller) pattern.

What is Cross Page Posting? How is it done?

 

By default, ASP.NET submits a form to the same page. In cross-page posting, the form is submitted to a different page. This is done by setting the �PostBackUrl� property of the button(that causes postback) to the desired page. In the code-behind of the page to which the form has been posted, use the �FindControl� method of the �PreviousPage� property to reference the data of the control in the first page.

what is marshling?

1. 
   Marshaling performs the necessary conversions in data formats between managed and unmanaged code.CLR allows managed code to interoperate with unmanaged code usining COM Marshaler(Component of CLR).

Name two properties common in every validation control?

1. 
   ControlToValidate property and Text property.

What methods are fired during the page load?

1. 
   Init() - when the page is instantiated
2. 
   Load() - when the page is loaded into server memory
3. 
   PreRender() - the brief moment before the page is displayed to the user as HTML
4. 
   Unload() - when page finishes loading.

What is the Global.asax used for?

1. 
   The Global.asax (including the Global.asax.cs file) is used to implement application and session level events.

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.

what is Boxing and UnBoxing ?

Boxing:
The conversion of a value type instance to an object, which implies that the instance will carry full type information at run time and will be allocated in the heap. The Microsoft intermediate language (MSIL) instruction set's box instruction converts a value type to an object by making a copy of the value type and embedding it in a newly allocated object.
Un-Boxing:
The conversion of an object instance to a value type.
Dim x As Integer
Dim y As Object
x = 10
boxing process
y = x
unboxing process
x = y

What is Reflection in .NET? Namespace?

 How will you load an assembly which is not referenced by current assembly?
All .NET compilers produce metadata about the types defined in the modules they produce. This metadata is packaged along with the module (modules in turn are packaged together in assemblies), and can be accessed by a mechanism called reflection. The System.Reflection namespace contains classes that can be used to interrogate the types for a module/assembly.
Using reflection to access .NET metadata is very similar to using ITypeLib/ITypeInfo to access type library data in COM, and it is used for similar purposes - e.g. determining data type sizes for marshaling data across context/process/machine boundaries.
Reflection can also be used to dynamically invoke methods (see System.Type.InvokeMember), or even create types dynamically at run-time (see System.Reflection.Emit.TypeBuilder).
Reflection generally means that a program can gain knowledge about its own structure. With .NET, Reflection describes the possibility - depending on security features - to detect mega data of a .NET-application and of the data types and functions contained therein.
During the runtime, it is therefore possible that an application can determine its own functionality. For example, an application could be developed, which can be extended by functionality through the adding of the respective Assemblies - without changing the main program.

What are Value types and Reference types ?

Reference Type:
Reference types are allocated on the managed CLR heap, just like object types.
A data type that is stored as a reference to the value's location. The value of a reference type is the location of the sequence of bits
that represent the type's data. Reference types can be self-describing types, pointer types, or interface types
Value Type:
Value types are allocated on the stack just like primitive types in VBScript, VB6 and C/C++. Value types are not instantiated using new go out of scope when the function they are defined within returns.
Value types in the CLR are defined as types that derive from system.valueType.
A data type that fully describes a value by specifying the sequence of bits that constitutes the value's representation. Type information for a value type instance is not stored with the instance at run time, but it is available in metadata. Value type instances can be treated as objects using boxing.
55. What is concept of Boxing and Unboxing ?

What is Manifest?

Every assembly, whether static or dynamic, contains a collection of data that describes how the elements in the assembly relate to each other. The assembly manifest contains this assembly metadata.

 An assembly manifest contains all the metadata needed to specify the assembly's version requirements and security identity, and all metadata needed to define the scope of the assembly and resolve references to resources and classes.

The assembly manifest can be stored in either a PE file (an .exe or .dll) with Microsoft intermediate language (MSIL) code or in a standalone PE file that contains only assembly manifest information.

What is Garbage collection?

Short  :

1. Garbage collection is a CLR feature which automatically release the  memory from the application .
2. Programmers forget to release the objects while coding. CLR automatically releases objects when they are no longer referenced and in use. CLR runs on non-deterministic to see the unused objects and cleans them.
3. The garbage collector (GC) completely absolves the developer from tracking memory usage and knowing when to free memory.

 ------------------------------------------------------------------------------------
Breifly :
Every program uses resources of one sort or another -- memory buffers, network connections, database resources and so on. In fact, in an object-oriented environment, every type identifies some resource available for a program's use. To use any of these resources, memory must be allocated to represent the type.

The steps required to access a resource are as follows:
1. Allocate memory for the type that represents the resource.
2. Initialize the memory to set the initial state of the resource and to make the resource usable.
3. Use the resource by accessing the instance members of the type (repeat as necessary).
4. Tear down the state of the resource to clean up.
5. Free the memory.

What is a CTS / Common Type System ?

Common Type System.

• Asp.net support a multi language . so asp.net provide a Common Type System for all language  (CTS)

• This is the range of types that the .NET runtime understands, and therefore that .NET applications can use.

• The CTS is a superset of the CLS.

•  Note :that not all .NET languages will support all the types in the CTS.

What is Namespace?

• Namespace  is a collection of classes  and  interfaces Namespace is a logical naming scheme for group related types.

•  A namespace can span multiple assemblies, and an assembly can define multiple namespaces. When the compiler needs the definition for a class type, it tracks through each of the different imported namespaces to the type name and searches each referenced assembly until it is found.

• Namespaces can be nested. This is very similar to packages in Java as far as scoping is concerned.

What is CLR ?

Common Language Runtime (CLR) is a run-time environment that manages the execution of .NET code and provides services like memory management, debugging, security, etc. The CLR is also known as Virtual Execution System (VES). The CLR is a multi-language execution environment. There are currently over 15 compilers being built by Microsoft and other companies that produce code that will execute in the CLR.
The Common Language Runtime (CLR) provides a solid foundation for developers to build various types of applications. Whether you're writing an ASP.Net application , a Windows Forms application, a Web Service, a mobile code application, a distributed application, or an application that combines several of these application models,

CLR provides the following benefits for application developers:

� Vastly simplified development
� Seamless integration of code written in various languages
� Evidence-based security with code identity
� Assembly-based deployment that eliminates DLL Hell
� Side-by-side versioning of reusable components
� Code reuse through implementation inheritance
� Automatic object lifetime management
� Self describing objects

What is CLS?

Common Language Specification.

This is a subset of the CTS which all .NET languages are expected to support. The idea is that any program which uses CLS-compliant types can interoperate with any .NET program written in any language.In theory this allows very tight interop between different .NET languages -

 for example allowing a C# class to inherit from a VB class.

.NET Framework Class Library

The .NET Framework class library is a collection of reusable types that tightly integrate with the common language runtime. The class library is object oriented, providing types from which your own managed code can derive functionality. This not only makes the .NET Framework types easy to use, but also reduces the time associated with learning new features of the .NET Framework. In addition, third-party components can integrate seamlessly with classes in the .NET Framework.

Whats the difference between Dataset.clone and Dataset.copy ?

The Clone method of the DataSet class copies only the schema of a DataSet object. It returns a new DataSet object that has the same schema as the existing DataSet object, including all DataTable schemas, relations, and constraints. It does not copy any data from the existing DataSet object into the new DataSet.

The Copy method of the DataSet class copies both the structure and data of a DataSet object. It returns a new DataSet object having the same structure (including all DataTable schemas, relations, and constraints) and data as the existing DataSet object.

How to use transactions in ADO.net?

Transactions are a feature offered by most enterprise-class databases for making sure data integrity is maintained when data is modified. A transaction at its most basic level consists of two required steps�Begin, and then either Commit or Rollback. The Begin call defines the start of the transaction boundary, and the call to either Commit or Rollback defines the end of it. Within the transaction boundary, all of the statements executed are considered to be part of a unit for accomplishing the given task, and must succeed or fail as one. Commit (as the name suggests) commits the data modifications if everything was successful, and Rollback undoes the data modifications if an error occurs. All of the .NET data providers provide similar classes and methods to accomplish these operations.

The ADO.NET data providers offer transaction functionality through the Connection, Command, and Transaction classes. A typical transaction would follow a process similar to this:

Open the transaction using Connection.BeginTransaction().
Enlist statements or stored procedure calls in the transaction by setting the Command.Transaction property of the Command objects associated with them.
Depending on the provider, optionally use Transaction.Save() or Transaction.Begin() to create a savepoint or a nested transaction to enable a partial rollback.
Commit or roll back the transaction using Transaction.Commit() or Transaction.Rollback().

What is CommandBuilder?

What the CommandBuilder can do is relieve you of the responsibility of writing your own action queries by automatically constructing the SQL code, ADO.NET Command objects, and their associated Parameters collections given a SelectCommand.

The CommandBuilder expects you to provide a viable, executable, and simple SelectCommand associated with a DataAdapter. It also expects a viable Connection. That's because the CommandBuilder opens the Connection associated with the DataAdapter and makes a round trip to the server each and every time it's asked to construct the action queries. It closes the Connection when it's done.


Dim cn As SqlConnection
Dim da As SqlDataAdapter
Dim cb As SqlCommandBuilder
cn = New SqlConnection("data source=demoserver�")
da = New SqlDataAdapter("SELECT Au_ID, au_lname, City FROM authors", cn)

Using Stored Procedures

Stored procedures offer many advantages in data-driven applications. Using stored procedures, database operations can be encapsulated in a single command, optimized for best performance, and enhanced with additional security. While a stored procedure can be called by simply passing the stored procedure name followed by parameter arguments as an SQL statement, using the Parameters collection of the ADO.NET Command object enables you to more explicitly define stored procedure parameters as well as to access output parameters and return values.
To call a stored procedure, set the CommandType of the Command object to StoredProcedure. Once the CommandType is set to StoredProcedure, you can use the Parameters collection to define parameters, as in the following example.
Note The OdbcCommand requires that you supply the full ODBC CALL syntax when calling a stored procedure.

What are the various objects in Dataset ?

Dataset has a collection of DataTable object within the Tables collection. Each DataTable object contains a collection of DataRow objects and a collection of DataColumn objects. There are also collections for the primary keys, constraints, and default values used in this table which is called as constraint collection, and the parent and child relationships between the tables. Finally, there is a DefaultView object for each table. This is used to create a Data View object based on the table, so that the data can be searched, filtered or otherwise manipulated while displaying the data.

What are the two fundamental objects in ADO.NET ?

Datareader and Dataset are the two fundamental objects in ADO.NET.

Explain DataSet.AcceptChanges and DataAdapter.Update methods?

Dataset maintains the rowstate of each row with in a table. as a dataset is loaded its rowstate version is unchanged . whenever there is a modification in a paricular row with in a datatable , dataset changes the rowversion as modified, Added or deleted based on the particular action performed on the particular row.
AcceptChanges() method again change the Rowversion back to Unchanged.

Update() method is for updation of any changes made to the dataset in the database. This function checks the rowversion of each row with in a table. If it finds any row with added rowstate then that particular row is inserted else if it is Modified it is upadted if deleted then a delete statement is executed.
But if Acceptchanges() is done before an update function it wold not update anything to database since rowstate becomes unchanged

What is Connection pooling?

The connection represents an open and unique link to a data source. In a distributed system, this often involves a network connection. Depending on the underlying data source, the programming interface of the various connection objects may differ quite a bit. A connection object is specific to a particular type of data source, such as SQL Server and Oracle. Connection objects can't be used interchangeably across different data sources, but all share a common set of methods and properties grouped in the IDbConnection interface.
In ADO.NET, connection objects are implemented within data providers as sealed classes (that is, they are not further inheritable). This means that the behavior of a connection class can never be modified or overridden, just configured through properties and attributes. In ADO.NET, all connection classes support connection pooling, although each class may implement it differently. Connection pooling is implicit, meaning that you don't need to enable it because the provider manages this automatically.
ADO.NET pools connections with the same connection or configuration (connection string). It can maintain more than one pool (actually, one for each configuration). An interesting note: Connection pooling is utilized (by default) unless otherwise specified. If you close and dispose of all connections, then there will be no pool (since there are no available connections).
While leaving database connections continuously open can be troublesome, it can be advantageous for applications that are in constant communication with a database by negating the need to re-open connections. Some database administrators may frown on the practice since multiple connections (not all of which may be useful) to the database are open. Using connection pooling depends upon available server resources and application requirements (i.e., does it really need it).
Using connection pooling
Connection pooling is enabled by default. You may override the default behavior with the pooling setting in the connection string. The following SQL Server connection string does not utilize connection pooling:
Data Source=TestServer;Initial Catalog=Northwind;
User ID=Chester;Password=Tester;Pooling=False;
You can use the same approach with other .NET Data Providers. You may enable it by setting it to True (or eliminating the Pooling variable to use the default behavior). In addition, the default size of the connection pool is 100, but you may override this as well with connection string variables. You may use the following variables to control the minimum and maximum size of the pool as well as transaction support:

� Max Pool Size: The maximum number of connections allowed in the pool. The default value is 100.
� Min Pool Size: The minimum number of connections allowed in the pool. The default value is zero.
� Enlist: Signals whether the pooler automatically enlists the connection in the creation thread's current transaction context. The default value is true.

The following SQL Server connection string uses connection pooling with a minimum size of five and a maximum size of 100:

Data Source=TestServer;Initial Catalog=Northwind;
User ID=Chester;Password=Tester;Max Pool Size=50;
Min Pool Size=5;Pooling=True;

Difference between SqlCommand and SqlCommandBuilder?

 Difference between SqlCommand and SqlCommandBuilder?

SQLCommand is used to retrieve or update the data from database.
You can use the SELECT / INSERT,UPDATE,DELETE command with SQLCommand. SQLCommand will execute these commnds in the database.

SQLBUILDER is used to build the SQL Command like SELECT/ INSERTR, UPDATE etc.

What are the different rowversions available?

There are four types of Rowversions.
Current:
The current values for the row. This row version does not exist for rows with a RowState of Deleted.
Default :
The row the default version for the current DataRowState. For a DataRowState value of Added, Modified or Current, the default version is Current. For a DataRowState of Deleted, the version is Original. For a DataRowState value of Detached, the version is Proposed.
Original:
The row contains its original values.
Proposed:
The proposed values for the row. This row version exists during an edit operation on a row, or for a row that is not part of a DataRowCollection

. What are different execute methods of ADO.NET command object?

ExecuteScalar method returns a single value from the first row and first column of the resultset obtained from the execution of SQL query.
ExecuteNonQuery method executes the DML SQL query such as insert, delete or update and returns the number of rows affected by this action.
ExecuteReader method returns DataReader object which is a forward-only resultset.
ExecuteXMLReader method is available for SQL Server 2000 or later. Upon execution it builds XMLReader object from standard SQL query.

What is the difference between data reader and data adapter?

DateReader is an forward only and read only cursor type if you are accessing data through DataRead it shows the data on the web form/control but you can not perform the paging feature on that record(because it's forward only type).
Reader is best fit to show the Data (where no need to work on data)
DataAdapter is not only connect with the Databse(through Command object) it provide four types of command (InsertCommand, UpdateCommand, DeleteCommand, SelectCommand), It supports to the disconnected Architecture of .NET show we can populate the records to the DataSet. where as Dataadapter is best fit to work on data.

What is Data Reader?

You can use the ADO.NET DataReader to retrieve a read-only, forward-only stream of data from a database. Using the DataReader can increase application performance and reduce system overhead because only one row at a time is ever in memory.
After creating an instance of the Command object, you create a DataReader by calling Command. ExecuteReader to retrieve rows from a data source, as shown in the following example.

SqlDataReader myReader = myCommand.ExecuteReader();

You use the Read method of the DataReader object to obtain a row from the results of the query.

while (myReader.Read())
Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));

What is Data Reader?

You can use the ADO.NET DataReader to retrieve a read-only, forward-only stream of data from a database. Using the DataReader can increase application performance and reduce system overhead because only one row at a time is ever in memory.
After creating an instance of the Command object, you create a DataReader by calling Command. ExecuteReader to retrieve rows from a data source, as shown in the following example.

SqlDataReader myReader = myCommand.ExecuteReader();

You use the Read method of the DataReader object to obtain a row from the results of the query.

while (myReader.Read())
Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));

What is Data Adapter?

The DataAdapter serves as a bridge between a DataSet and a data source for retrieving and saving data. The DataAdapter provides this bridge by mapping Fill, which changes the data in the DataSet to match the data in the data source, and Update, which changes the data in the data source to match the data in the DataSet. If you are connecting to a Microsoft SQL Server database, you can increase overall performance by using the SqlDataAdapter along with its associated SqlCommand and SqlConnection. For other OLE DB-supported databases, use the DataAdapter with its associated OleDbCommand and OleDbConnection objects.

What are the differences between the Recordset and the DataSet objects?

Tables represented by the object: The ADO Recordset object represents only one table at a given time, while the DataSet object in ADO.NET can represent any number of tables, keys, constraints and relations which makes it very much like an RDBMS.
Navigation: Navigating the Recordset object depend on the cursor used to create the object with limited functionality in moving back and forth while the DataSet represents data in �collections� that could be accessed through indexers in a random-access fashion
Connection Model: The Recordset is designed to work as a �connected object� with a server-side cursor in mind while the DataSet is designed to work as a disconnected object containing hierarchy of data in XML format.

Database Updates: Updating a database through the use of a Recordset object is direct since it is tied to the database. On the other hand, the DataSet as an independent data store must use a database-specific DataAdapter object to post updates to the database.

Differences Between ADO and ADO.NET

ADO.NET is an evolution of ADO. The following table lists several data access features and how each feature differs between ADO and ADO.NET.

Feature
ADO
ADO.NET
Memory-resident data representation
Uses the Recordset object, which holds single rows of data, much like a database table
Uses the DataSet object, which can contain one or more tables represented by DataTable objects
Relationships between multiple tables
Requires the JOIN query to assemble data from multiple database tables in a single result table. Also offers hierarchical recordsets, but they are hard to use
Supports the DataRelation object to associate rows in one DataTable object with rows in another DataTable object
Data navigation
Traverses rows in a Recordset sequentially, by using the .MoveNext method
The DataSet uses a navigation paradigm for nonsequential access to rows in a table. Accessing the data is more like accessing data in a collection or array. This is possible because of the Rows collection of the DataTable; it allows you to access rows by index. Follows relationships to navigate from rows in one table to corresponding rows in another table
Disconnected access
Provided by the Recordset but it has to be explicitly coded for. The default for a Recordset object is to be connected via the ActiveConnection property. You communicate to a database with calls to an OLE DB provider
Communicates to a database with standardized calls to the DataAdapter object, which communicates to an OLE DB data provider, or directly to a SQL Server data provider
Programmability
All Recordset field data types are COM Variant data types, and usually correspond to field names in a database table
Uses the strongly typed programming characteristic of XML. Data is self-describing because names for code items correspond to the business problem solved by the code. Data in DataSet and DataReader objects can be strongly typed, thus making code easier to read and to write
Sharing disconnected data between tiers or components
Uses COM marshaling to transmit a disconnected record set. This supports only those data types defined by the COM standard. Requires type conversions, which demand system resources
Transmits a DataSet as XML. The XML format places no restrictions on data types and requires no type conversions
Transmitting data through firewalls
Problematic, because firewalls are typically configured to prevent system-level requests such as COM marshaling
Supported, because ADO.NET DataSet objects use XML, which can pass through firewalls
Scalability
Since the defaults in ADO are to use connected Recordset objects, database locks, and active database connections for long durations contend for limited database resources
Disconnected access to database data without retaining database locks or active database connections for lengthy periods limits contention for limited database resources

Whate are different types of Commands available with DataAdapter ?

The SqlDataAdapter has four command objects

SelectCommand
InsertCommand
DeleteCommand
UpdateCommand

What is a Dataset?

Major component of ADO.NET is the DataSet object, which you can think of as being similar to an in-memory relational database. DataSet objects contain DataTable objects, relationships, and constraints, allowing them to replicate an entire data source, or selected parts of it, in a disconnected fashion.
A DataSet object is always disconnected from the source whose data it contains, and as a consequence it doesn't care where the data comes from�it can be used to manipulate data from a traditional database or an XML document, or anything in between. In order to connect a DataSet to a data source, you need to use a data adapter as an intermediary between the DataSet and the .NET data provider.


The dataset is a disconnected in-memory cache database. The dataset object model looks like this:
Dataset
DataTableCollection
DataTable
DataView
DataRowCollection
DataRow
DataColumnCollection
DataColumn
ChildRelations
ParentRelations
Constraints
PrimaryKey
DataRelationCollection
Let�s take a look at each of these:
DataTableCollection: As we say that a DataSet is an in-memory database. So it has this collection, which holds data from multiple tables in a single DataSet object.
DataTable: In the DataTableCollection, we have DataTable objects, which represents the individual tables of the dataset.
DataView: The way we have views in database, same way we can have DataViews. We can use these DataViews to do Sort, filter data.
DataRowCollection: Similar to DataTableCollection, to represent each row in each Table we have DataRowCollection.
DataRow: To represent each and every row of the DataRowCollection, we have DataRows.
DataColumnCollection: Similar to DataTableCollection, to represent each column in each Table we have DataColumnCollection.
DataColumn: To represent each and every Column of the DataColumnCollection, we have DataColumn.
PrimaryKey: Dataset defines Primary key for the table and the primary key validation will take place without going to the database.
Constraints: We can define various constraints on the Tables, and can use Dataset.Tables(0).enforceConstraints. This will execute all the constraints, whenever we enter data in DataTable.
DataRelationCollection: as we know that we can have more than 1 table in the dataset, we can also define relationship between these tables using this collection and maintain a parent-child relationship.

4. Explain what a diffgram is and its usage ?

A DiffGram is an XML format that is used to identify current and original versions of data elements. The DataSet uses the DiffGram format to load and persist its contents, and to serialize its contents for transport across a network connection. When a DataSet is written as a DiffGram, it populates the DiffGram with all the necessary information to accurately recreate the contents, though not the schema, of the DataSet, including column values from both the Original and Current row versions, row error information, and row order.
When sending and retrieving a DataSet from an XML Web service, the DiffGram format is implicitly used. Additionally, when loading the contents of a DataSet from XML using the ReadXml method, or when writing the contents of a DataSet in XML using the WriteXml method, you can select that the contents be read or written as a DiffGram.

Explain ACID properties?.

The ACID model is one of the oldest and most important concepts of database theory. It sets forward four goals that every database management system must strive to achieve: atomicity, consistency, isolation and durability. No database that fails to meet any of these four goals can be considered reliable.
Let�s take a moment to examine each one of these characteristics in detail:

Atomicity states that database modifications must follow an �all or nothing� rule. Each transaction is said to be �atomic.� If one part of the transaction fails, the entire transaction fails. It is critical that the database management system maintain the atomic nature of transactions in spite of any DBMS, operating system or hardware failure.

Consistency states that only valid data will be written to the database. If, for some reason, a transaction is executed that violates the database�s consistency rules, the entire transaction will be rolled back and the database will be restored to a state consistent with those rules. On the other hand, if a transaction successfully executes, it will take the database from one state that is consistent with the rules to another state that is also consistent with the rules.

Isolation requires that multiple transactions occurring at the same time not impact each other�s execution. For example, if Joe issues a transaction against a database at the same time that Mary issues a different transaction, both transactions should operate on the database in an isolated manner. The database should either perform Joe�s entire transaction before executing Mary�s or vice-versa. This prevents Joe�s transaction from reading intermediate data produced as a side effect of part of Mary�s transaction that will not eventually be committed to the database. Note that the isolation property does not ensure which transaction will execute first, merely that they will not interfere with each other.

Durability ensures that any transaction committed to the database will not be lost. Durability is ensured through the use of database backups and transaction logs that facilitate the restoration of committed transactions in spite of any subsequent software or hardware failures.

Explain ADO.Net Architecture ??

ADO.NET Architecture includes three data providers for implementing connectivity with databases: SQL Server .NET Data Provider, OLEDB .NET Data Provider, and ODBC .Net Data Provider. You can access data through data provider in two ways either using a DataReader or DataAdapter.

Data Access in ADO.NET relies on two components:

1 DataSet
2.Data Provider.

DataSet

The ADO.NET Data Set is explicitly designed for data access independent of any data source. As a result, it can be used with multiple and differing data sources, used with XML data, or used to manage data local to the application. The DataSet contains a collection of one or more objects made up of rows and columns of data, as well as primary key, foreign key, constraint, and relation information about the data in the DataTable objects.
The dataset is a disconnected, in-memory representation of data. It can be considered as a local copy of the relevant portions of the database. The DataSet is persisted in memory and the data in it can be manipulated and updated independent of the database. When the use of this DataSet is finished, changes can be made back to the central database for updating. The data in DataSet can be loaded from any valid data source like Microsoft SQL server database, an Oracle database or from a Microsoft Access database.

Data Provider
'
The Data Provider is responsible for providing and maintaining the connection to the database. A DataProvider is a set of related components that work together to provide data in an efficient and performance driven manner. The .NET Framework currently comes with two DataProviders: the SQL Data Provider which is designed only to work with Microsoft's SQL Server 7.0 or later and the OleDb DataProvider which allows us to connect to other types of databases like Access and Oracle. Each DataProvider consists of the following component classes:
The Connection object which provides a connection to the database
The Command object which is used to execute a command
The DataReader object which provides a forward-only, read only, connected recordset
The DataAdapter object which populates a disconnected DataSet with data and performs update

Data access with ADO.NET can be summarized as follows:
A connection object establishes the connection for the application with the database. The command object provides direct execution of the command to the database. If the command returns more than a single value, the command object returns a DataReader to provide the data. Alternatively, the DataAdapter can be used to fill the Dataset object. The database can be updated using the command object or the DataAdapter.
Component classes that make up the Data Providers
The Connection ObjectThe Connection object creates the connection to the database. Microsoft Visual Studio .NET provides two types of Connection classes: the SqlConnection object, which is designed specifically to connect to Microsoft SQL Server 7.0 or later, and the OleDbConnection object, which can provide connections to a wide range of database types like Microsoft Access and Oracle. The Connection object contains all of the information required to open a connection to the database.
The Command Object
The Command object is represented by two corresponding classes: SqlCommand and OleDbCommand. Command objects are used to execute commands to a database across a data connection. The Command objects can be used to execute stored procedures on the database, SQL commands, or return complete tables directly. Command objects provide three methods that are used to execute commands on the database:

ExecuteNonQuery: Executes commands that have no return values such as INSERT, UPDATE or DELETE
ExecuteScalar: Returns a single value from a database query
ExecuteReader: Returns a result set by way of a DataReader object

The DataReader Object
The DataReader object provides a forward-only, read-only, connected stream recordset from a database. Unlike other components of the Data Provider, DataReader objects cannot be directly instantiated. Rather, the DataReader is returned as the result of the Command object's ExecuteReader method. The SqlCommand.ExecuteReader method returns a SqlDataReader object, and the OleDbCommand.ExecuteReader method returns an OleDbDataReader object. The DataReader can provide rows of data directly to application logic when you do not need to keep the data cached in memory. Because only one row is in memory at a time, the DataReader provides the lowest overhead in terms of system performance but requires the exclusive use of an open Connection object for the lifetime of the DataReader.
The DataAdapter Object
The DataAdapter is the class at the core of ADO .NET's disconnected data access. It is essentially the middleman facilitating all communication between the database and a DataSet. The DataAdapter is used either to fill a DataTable or DataSet with data from the database with it's Fill method. After the memory-resident data has been manipulated, the DataAdapter can commit the changes to the database by calling the Update method. The DataAdapter provides four properties that represent database commands:
SelectCommand
InsertCommand
DeleteCommand
UpdateCommand
When the Update method is called, changes in the DataSet are copied back to the database and the appropriate InsertCommand, DeleteCommand, or UpdateCommand is executed.

What is UDDI?

UDDI (Universal Description, Discovery, and Integration) currently represents the discovery layer within the Web services protocol stack.

UDDI was originally created by Microsoft, IBM, and Ariba, and represents a technical specification for publishing and finding businesses and Web services.

At its core, UDDI consists of two parts.

First, UDDI is a technical specification for building a distributed directory of businesses and Web services. Data is stored within a specific XML format, and the UDDI specification includes API details for searching existing data and publishing new data.

Second, the UDDI Business Registry is a fully operational implementation of the UDDI specification. Launched in May 2001 by Microsoft and IBM, the UDDI registry now enables anyone to search existing UDDI data. It also enables any company to register themselves and their services.

The data captured within UDDI is divided into three main categories:

White Pages: This includes general information about a specific company. For example, business name, business description, and address.

Yellow Pages: This includes general classification data for either the company or the service offered. For example, this data may include industry, product, or geographic codes based on standard taxonomies.

Green Pages: This includes technical information about a Web service. Generally, this includes a pointer to an external specification, and an address for invoking the Web service.

You can view the Microsoft UDDI site, or the IBM UDDI site. The complete UDDI specification is available at uddi.org.

What is DOM and how does it relate to XML?

The Document Object Model (DOM) is an interface specification maintained
by the W3C DOM Workgroup that defines an application independent
mechanism to access, parse, or update XML data. In simple terms
it is a hierarchical model that allows developers to manipulate
XML documents easily Any developer that has worked extensively with
XML should be able to discuss the concept and use of DOM objects
freely. Additionally, it is not unreasonable to expect advanced
candidates to thoroughly understand its internal workings and be
able to explain how DOM differs from an event-based interface like
SAX.

What is SOAP and how does it relate to XML?

The Simple Object Access Protocol (SOAP) uses XML to define a protocol
for the exchange of information in distributed computing environments.
SOAP consists of three components: an envelope, a set of encoding
rules, and a convention for representing remote procedure calls.
Unless experience with SOAP is a direct requirement for the open
position, knowing the specifics of the protocol, or how it can be
used in conjunction with HTTP, is not as important as identifying
it as a natural application of XML.

Difference between XML and HTML

1) XML is not a replacement for HTML.
2) XML and HTML were designed with different goals.
3) XML was designed to describe data and to focus on what data is.
4) HTML was designed to display data and to focus on how data looks.
5) HTML is about displaying information, XML is about describing information

XML

User definable tags
Content driven
End tags required for well formed documents
Quotes required around attributes values
Slash required in empty tags

HTML
Defined set of tags designed for web display
Format driven
End tags not required
Quotes not required
Slash not required

What is XML?

XML is the Extensible Markup Language. It improves the functionality
of the Web by letting you identify your information in a more accurate,
flexible, and adaptable way. It is extensible because it is not
a fixed format like it�s written in SGML, the international standard meta language for
text document markup (ISO 8879).

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; the 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.
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.

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.

What is Index? and Types

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.

Clustered indexes define the physical sorting of a database table�s rows in the storage media. For this reason, each database table may have only one clustered index.
Non-clustered indexes are created outside of the database table and contain a sorted list of references to the table itself.

What is normalization? Different types

Database normalization is a data design and organization process applied to data structures based on rules that help build relational databases. In relational database design, the process of organizing data to minimize redundancy. 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.

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.

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

BCNF: Boyce-Codd Normal Form :If there are non-trivial dependencies between candidate key attributes, separate them out into distinct tables.

ONF: Optimal Normal Form

Relation Ship in Sql Server

One-to-One relationship can be implemented as a single table and rarely as two tables with primary and foreign key relationships.

One-to-Many relationships are implemented by splitting the data into two tables with primary key and foreign key relationships.

Many-to-Many relationships are implemented using a junction table with the keys from both the tables forming the composite primary key of the junction table.

What�s the difference between a primary key and a unique key?

Both primary key and unique enforce 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.

What�s the difference between a primary key and a unique key?

Both primary key and unique enforce 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.

What is 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 result set. 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.

What are types of sub-queries?

Single-row subquery, where the subquery returns only one row.
Multiple-row subquery, where the subquery returns multiple rows,.and
Multiple column subquery, where the subquery returns multiple columns.

What is cursors?

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

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.

Types of joins:

 INNER JOINs,
OUTER JOINs,
CROSS JOINs.
OUTER JOINs
 LEFT OUTER JOINS,
RIGHT OUTER JOINS
FULL OUTER JOINS.

What is difference between DELETE & 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 and its columns, constraints, indexes and so on remain. 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 can not be Rolled back using logs.
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 using logs.
DELETE is DML Command.
DELETE does not reset identity of the table.
Difference between Function and Stored Procedure?

What is the difference between a HAVING CLAUSE and a WHERE CLAUSE?

Specifies a search condition for a group or an aggregate. HAVING can be used only with the SELECT statement. HAVING is typically used in a GROUP BY clause. When GROUP BY is not used, HAVING behaves like a WHERE clause. Having Clause is basically used only with the GROUP BY function in a query. WHERE Clause is applied to each row before they are part of the GROUP BY function in a query. HAVING criteria is applied after the the grouping of rows has occurred.

What is the difference between a local and a global variable?

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 are 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.

What kind of User-Defined Functions can be created?

There are three types of User-Defined functions in SQL Server 2000 and they are Scalar, Inline Table-Valued and Multi-statement Table-valued.
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 T-SQL 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.