LINQ

LINQ stands for Language Integrated Query.

Language-Integrated Query (LINQ) is an innovation introduced in Visual Studio 2008 and .NET Framework version 3.5 that bridges the gap between the world of objects and the world of data.

You can use LINQ queries in new projects, or alongside non-LINQ queries in existing projects. The only requirement is that the project target .NET Framework 3.5 or later.

This is a Microsoft programming model and methodology that offers developers a way to manipulate data using a succinct yet expressive syntax. It does so by instilling Microsoft .NET-based programming languages with the ability to make formal queries

In Visual Studio you can write LINQ queries in Visual Basic or C# with SQL Server databases, XML documents, ADO.NET Datasets, and any collection of objects that supports IEnumerable or the generic IEnumerable<T> interface. LINQ support for the ADO.NET Entity Framework is also planned, and LINQ providers are being written by third parties for many Web services and other database implementations.

WCF

WCF stands for Windows Communication Foundation.It is a framework for building, configuring, and deploying network-distributed services

WCF was released for the first time in 2006 as a part of the .NET framework with Windows Vista, and then got updated several times. WCF 4.5 is the most recent version that is now widely used.

A WCF application consists of three components:

• WCF service,
• WCF service host, and
• WCF service client.

Fundamental Concepts of WCF

Message

This is a communication unit that comprises of several parts apart from the body. Message instances are sent as well as received for all types of communication between the client and the service.

Endpoint

It defines the address where a message is to be sent or received. It also specifies the communication mechanism to describe how the messages will be sent along with defining the set of messages. A structure of an endpoint comprises of the following parts:

• Address - Address specifies the exact location to receive the messages and is specified as a Uniform Resource Identifier (URI). It is expressed as scheme://domain[:port]/[path]. Take a look at the address mentioned below:
  net.tcp://localhost:9000/ServiceA
  Here, 'net.tcp' is the scheme for the TCP protocol. The domain is 'localhost' which can be the name of a machine or a web domain, and the path is 'ServiceA'.

• Binding - It defines the way an endpoint communicates. It comprises of some binding elements that make the infrastructure for communication. For example, a binding states the protocols used for transport like TCP, HTTP, etc., the format of message encoding, and the protocols related to security as well as reliability.
• Contracts - It is a collection of operations that specifies what functionality the endpoint exposes to the clinet. It generally consists of an interface name.

Hosting

Hosting from the viewpoint of WCF refers to the WCF service hosting which can be done through many available options like self-hosting, IIS hosting, and WAS hosting.

Metadata

This is a significant concept of WCF, as it facilitates easy interaction between a client application and a WCF service. Normally, metadata for a WCF service is generated automatically when enabled, and this is done by inspection of service and its endpoints.

WCF Client

A client application that gets created for exposing the service operations in the form of methods is known as a WCF client. This can be hosted by any application, even the one that does service hosting.

Channel

Channel is a medium through which a client communicates with a service. Different types of channels get stacked and are known as Channel Stacks.

SOAP

Although termed as ‘Simple Object Access Protocol’, SOAP is not a transport protocol; instead it is an XML document comprising of a header and body section.

Advantages of WCF

• It is interoperable with respect to other services. This is in sharp contrast to .NET Remoting in which both the client and the service must have .Net.
• WCF services offer enhanced reliability as well as security in comparison to ASMX (Active Server Methods) web services.
• Implementing the security model and binding change in WCF do not require a major change in coding. Just a few configuration changes is required to meet the constraints.
• WCF has built-in logging mechanism whereas in other technologies, it is essential to do the requisite coding.
• WCF has integrated AJAX and support for JSON (JavaScript object notation).
• It offers scalability and support for up-coming web service standards.
• It has a default security mechanism which is extremely robust.

difference between WCF and Web services

Features	Web Service	WCF
Hosting	It can be hosted in IIS	It can be hosted in IIS, windows activation service, Self-hosting, Windows service
Programming	[WebService] attribute has to be added to the class	[ServiceContraact] attribute has to be added to the class
Model	[WebMethod] attribute represents the method exposed to client	[OperationContract] attribute represents the method exposed to client
Operation	One-way, Request- Response are the different operations supported in web service	One-Way, Request-Response, Duplex are different type of operations supported in WCF
XML	System.Xml.serialization name space is used for serialization	System.Runtime.Serialization namespace is used for serialization
Encoding	XML 1.0, MTOM(Message Transmission Optimization Mechanism), DIME, Custom	XML 1.0, MTOM, Binary, Custom
Transports	Can be accessed through HTTP, TCP, Custom	Can be accessed through HTTP, TCP, Named pipes, MSMQ,P2P, Custom
Protocols	Security	Security, Reliable messaging, Transactions

SQL Server CROSS APPLY and OUTER APPLY

Creating some temporary objects

CREATE TABLE ##Department( 

   [DepartmentID] [int] NOT NULL PRIMARY KEY, 

   [Name] VARCHAR(250) NOT NULL, 

) ON [PRIMARY] 

INSERT ##Department ([DepartmentID], [Name])  

VALUES (1, N'Engineering') 

INSERT ##Department ([DepartmentID], [Name])  

VALUES (2, N'Administration') 

INSERT ##Department ([DepartmentID], [Name])  

VALUES (3, N'Sales') 

INSERT ##Department ([DepartmentID], [Name])  

VALUES (4, N'Marketing') 

INSERT ##Department ([DepartmentID], [Name])  

VALUES (5, N'Finance') 

GO 

CREATE TABLE ##Employee( 

   [EmployeeID] [int] NOT NULL PRIMARY KEY, 

   [FirstName] VARCHAR(250) NOT NULL, 

   [LastName] VARCHAR(250) NOT NULL, 

   [DepartmentID] [int] NOT NULL , 

) ON [PRIMARY] 

GO 

INSERT ##Employee ([EmployeeID], [FirstName], [LastName], [DepartmentID]) 

VALUES (1, N'Sendhil', N'Kumar', 1 ) 

INSERT ##Employee ([EmployeeID], [FirstName], [LastName], [DepartmentID]) 

VALUES (2, N'Arun', N'Kumar', 2 ) 

INSERT ##Employee ([EmployeeID], [FirstName], [LastName], [DepartmentID]) 

VALUES (3, N'Vivek', N'Ram', 3 ) 

INSERT ##Employee ([EmployeeID], [FirstName], [LastName], [DepartmentID]) 

VALUES (4, N'Bill', N'Gates', 3 )

CROSS APPLY and INNER JOIN

SELECT * FROM ##Department D 

CROSS APPLY 

   ( 

   SELECT * FROM ##Employee E 

   WHERE E.DepartmentID = D.DepartmentID 

   ) A 

GO 

SELECT * FROM ##Department D 

INNER JOIN ##Employee E ON D.DepartmentID = E.DepartmentID 

GO

OUTER APPLY and LEFT OUTER JOIN

SELECT * FROM ##Department D 

OUTER APPLY 

   ( 

   SELECT * FROM ##Employee E 

   WHERE E.DepartmentID = D.DepartmentID 

   ) A 

GO 

SELECT * FROM ##Department D 

LEFT OUTER JOIN ##Employee E ON D.DepartmentID = E.DepartmentID 

GO 

Difference between String and string in c#

There is no such difference between string and String (Syetem.String). The "string" keyword is an alias for System.String in the .NET Framework. So the String and string are equal and you can use whichever naming convention you prefer.

Difference between correlated subqueries and uncorrelated subqueries

Uncorrelated Subquery

If the SQL above looks scary to you, don’t worry – it’s still easy to understand for our purposes here. The subquery portion of the SQL above begins after the “NOT IN” statement. The reason that the query above is an uncorrelated subquery is that the subquery can be run independently of the outer query. Basically, the subquery has no relationship with the outer query.

Example:

Select  * from salesperson where salesperson.ID NOT IN (Select o.id from orders o,customer c where o.id=c.id)

Correlated Subquery

Now, a correlated subquery has the opposite property – the subquery can not be run independently of the outer query. You can take a look at this example of a correlated subquery below and easily see the difference yourself

Example:

Select * from  Employee e where (1)=(select count (distinct(e.salary)) from employee e1 where e1.salary>e.salary)

What you will notice in the correlated subquery above is that the inner subquery uses e.Salary, but the alias e is created in the outer query. This is why it is called a correlated subquery, because the subquery references a value in it’s WHERE clause (in this case, it uses a column belonging to e) that is used in the outer query.

Example

create table ##Emptemp(id int identity(1,1),Name Varchar(50),Dept varchar(50)) 

insert into ##Emptemp (name,dept) values ('Sendhil','ECE')

insert into ##Emptemp (name,dept) values ('Kumar','ECE')

insert into ##Emptemp (name,dept) values ('ARUN','EEE')

create table ##Deptemp(id int identity(1,1),DEP_Name Varchar(50)) 

insert into ##Deptemp (DEP_Name) values ('ECE')

insert into ##Deptemp (DEP_Name) values ('EEE')

select *  from ##Emptemp

select *  from ##Deptemp

Correlated Query:

select DEP_Name,(select COUNT(*) from ##Emptemp e where e.Dept=d.DEP_Name) TotalCount from ##Deptemp d

Uncorrelated Query:

select * from ##Emptemp e where e.Dept in (select d.DEP_Name  from ##Deptemp d )

Enter Username And Password Using VBscript

Call the Vbscript file using batch file

Batch File :

REM :Start
Pause
call  "C:\Users\sendhil\Desktop\Test\test2.vbs"
Pause

VBscript Code :

WScript.Quit Main

Function Main
  Set IE = WScript.CreateObject("InternetExplorer.Application", "IE_")
  IE.Visible = True
  IE.Navigate "http://default/Login.aspx"
  Wait IE
  With IE.Document
    .getElementByID("txtusername").value = "admin1"
    .getElementByID("txtpwd").value = "XXXX"
    .getElementsByName("btnok").Item(0).Click


  End With

 
End Function

Sub Wait(IE)
  Do
    WScript.Sleep 500
  Loop While IE.ReadyState < 4 And IE.Busy
  Do
    WScript.Sleep 500
  Loop While IE.ReadyState < 4 And IE.Busy
End Sub

Sub IE_OnQuit
  On Error Resume Next
  WScript.StdErr.WriteLine "IE closed before script finished."
  WScript.Quit
End Sub

ViewData VS ViewBag Vs TempData in MVC

ViewData and ViewBag are used for the same purpose to transfer data from controller to view. Both life lies only in current request. ViewData is nothing but dictionary of object and it is accessible by string as key. ViewData is property of controller that exposes an instance of the ViewDataDictionary class. ViewBag is very similar to ViewData. ViewBag is a dynamic property (dynamic keyword which is introduced in .net framework 4.0). ViewBag is able to set and get value dynamically and able to add any number of additional fields without converts it to strongly typed. ViewBag is just a wrapper around the ViewData.

 
ViewData Example

//Controller Code

public ActionResult Index()

{

      List<string> Student = new List<string>();

      Student.Add("Jignesh");

      Student.Add("Tejas");

      Student.Add("Rakesh");

      ViewData["Student"] = Student;

      return View();

}

//page code

<ul>

    <% foreach (var student in ViewData["Student"] asList<string>)

        { %>

    <li><%: student%></li>

    <% } %>

</ul>
 ViewBag Example

//Controller Code

public ActionResult Index()

{

      List<string> Student = new List<string>();

      Student.Add("Jignesh");

      Student.Add("Tejas");

      Student.Add("Rakesh");

      ViewBag.Student = Student;

      return View();

} 

//page code

<ul>

    <% foreach (var student in ViewBag.Student)

        { %>

    <li><%: student%></li>

    <% } %>

</ul>
 
TempData is a dictionary which is derived from TempDataDictionary class. TempData is stored data just like live session for short time. TempData Keep data for the time of HTTP Request it mean that it hold data between two consecutive requests. TempData help us to transfer data between controllers or between actions. TempData internally use Session variables. Note that TempData is only work during the current and subsequent request. It is generally used to store one time message. With the help of TempData.Keep() method we can keep value in TempData object after request completion.
 TempData Example
 

//Controller Code

public ActionResult Index()

{

    List<string> Student = new List<string>();

    Student.Add("Jignesh");

    Student.Add("Tejas");

    Student.Add("Rakesh");

    TempData["Student"] = Student;

    return View();

}

//page code

<ul>

    <% foreach (var student in TempData["Student"] asList<string>)

        { %>

    <li><%: student%></li>

    <% } %>

</ul>

ViewData VS ViewBag VS TempData
 

ViewData	ViewBag	TempData
It is Key-Value Dictionary collection	It is a type object	It is Key-Value Dictionary collection
ViewData is a dictionary object and it is property of ControllerBase class	ViewBag is Dynamic property of ControllerBase class.	TempData is a dictionary object and it is property of controllerBase class.
ViewData is Faster than ViewBag	ViewBag is slower than ViewData	NA
ViewData is introduced in MVC 1.0 and available in MVC 1.0 and above	ViewBag is introduced in MVC 3.0 and available in MVC 3.0 and above	TempData is also introduced in MVC1.0 and available in MVC 1.0 and above.
ViewData  is also work with .net framework 3.5 and above	ViewBag  is only  work with .net framework 4.0 and above	TempData  is also work with .net framework 3.5 and above
Type Conversion code is required while enumerating	In depth, ViewBag is used dynamic, so there is no need to type conversion while enumerating.	Type Conversion code is required while enumerating
It value become null if redirection is occurred.	Same as ViewData	TempData is used to pass data between two consecutive requests.
It lies only during the current request.	Same as ViewData	TempData is only work during the current and subsequent request