C# SQL Server CLR example.

clrExample.cs

using Microsoft.SqlServer.Server;
//------------------------------------------------------------------------------
// <copyright file="CSSqlClassFile.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Data.SqlTypes;
using System.IO;
using System.Net;
using System.Text;


public class CLRExample
{

/*
*params
*postdata-post data from SQL server. can be a single item or  JSON String 
*returnVal- The response returned form the Web API to SQL server
*
*/

    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void postData(SqlString postData, out SqlString returnval)
    {
        string feedData = string.Empty;
        try
        {
            string API_END_POINT = "YOUR END POINT URL";

            HttpWebRequest request = null;
            HttpWebResponse response = null;
            Stream stream = null;
            StreamReader streamReader = null;
            request = (HttpWebRequest)WebRequest.Create(url);

            
/* If you are using a proxy server then set ypur proxy server ip and port.*/
            WebProxy proxyObject = new WebProxy("proxy server ip and port", true);
            proxyObject.Credentials = CredentialCache.DefaultCredentials;

            request.Proxy = proxyObject;
            request.UserAgent = "CLR web client on SQL Server";
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            //if you have any headers add them to the request.
           // request.Headers.Add("header key", "value");

            byte[] byteArray = Encoding.UTF8.GetBytes(postData.ToString());
            request.ContentLength = byteArray.Length;
            Stream dataStream = request.GetRequestStream();
            dataStream.Write(byteArray, 0, byteArray.Length);
            dataStream.Close();

            response = (HttpWebResponse)request.GetResponse();
            stream = response.GetResponseStream();
            streamReader = new StreamReader(stream);
            feedData = streamReader.ReadToEnd();
            response.Close();
            stream.Dispose();
            streamReader.Dispose();
        }
        catch (Exception ex)
        {
            SqlContext.Pipe.Send(ex.Message.ToString());
        }
        returnval = feedData;
    }

}

clrProcedure.sql

CREATE PROCEDURE [dbo].[postData]
	  @postData NVARCHAR(4000),
      @returnval NVARCHAR(2000) OUTPUT
	 
WITH EXECUTE AS CALLER
AS
EXTERNAL NAME [CLRAssembly].[CLRExample].[postData]

--After creating the clrExample.cs class in visual studio generate a dll file that you add into your
--SQL server with the name CLRAssembly.
--this name depends on the name of your project its not neccessarily CLRAssembly.
--To add the assembly in your database expand the database->Programmatically->Assemblies->Right Click -> Add Assembly.
--Navigate to the location of your 
--assembly file then click Ok to add the assembly.

--[CLRExample]-> name of the class in clrExample.cs
--[postData]->name of your method.

--In order to use your assembly you may need to set the UNSAFE/ UNRESTRICTED permission while adding it in your database.
--This requires
--asymetric key which you can generate using the following query. 


USE MASTER
GO

CREATE 
    ASYMMETRIC KEY CLRAssembly 
    FROM EXECUTABLE FILE = N'PATH TO YOUR DLL \CLRAssembly.dll'   


CREATE LOGIN [ClrPermissionsLogin]
  FROM ASYMMETRIC KEY CLRAssembly;

GRANT UNSAFE ASSEMBLY TO [ClrPermissionsLogin];