Being the SQL junky that I am, I was interested in trying out SQL Server’s new CLR Stored Procedures. A CLR sproc is a stored procedure that is able to use .net code that you’ve compiled into an assembly file. For you classic ASP heads out there, think of the ASP page being the sproc, and the .net assembly being your COM object ( cringe, let’s talk about classic ASP ). While there are plenty of great articles on writing CLR stored procedures, I’m going to breeze through the code that makes up this project.

First make a .net class library that will be compiled into an assembly file.

using System;
using Microsoft.SqlServer.Server;
using System.Data.SqlTypes;
using System.Net;
using System.IO;
using System.Text.RegularExpressions;

/// <summary>
/// This assembly will be used by a SQL2005 SPROC to communicate
/// with twitter.com
/// </summary>
public sealed class tweetsproc
{
    /*
     * TWITTER CODE BORROWED FROM :
     *  http://www.dreamincode.net/code/snippet2556.htm
     *
     * A function to post an update to Twitter programmatically
     * Author: Danny Battison
     * Contact: gabehabe@hotmail.com
     */

    /// <summary>
    /// Post an update to a Twitter acount
    /// </summary>
    /// <param name="username">The username of the account</param>
    /// <param name="password">The password of the account</param>
    /// <param name="tweet">The status to post</param>
    [Microsoft.SqlServer.Server.SqlProcedure(Name = "PostTweet")]
    //public static void PostTweet( string username, string password, string tweet)
    public static void PostTweet(   SqlString username,
                                    SqlString password,
                                    SqlString tweet)
    {
        try
        {
            // encode the username/password
            string user = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(username.ToString() + ":" + password.ToString()));
            // determine what we want to upload as a status
            byte[] bytes = System.Text.Encoding.ASCII.GetBytes("status=" + tweet.ToString());

            // Create a WebPermission.
            WebPermission myWebPermission1 = new WebPermission();

            // Allow Connect access to the specified URLs.
            myWebPermission1.AddPermission(NetworkAccess.Connect,new Regex("http://www\\.twitter\\.com/.*",
              RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.Singleline));

            myWebPermission1.Demand();

            // connect with the update page
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://twitter.com/statuses/update.xml");

            // set the method to POST
            request.Method = "POST";
            request.ServicePoint.Expect100Continue = false; // thanks to argodev for this recent change!
            // set the authorisation levels
            request.Headers.Add("Authorization", "Basic " + user);
            request.ContentType = "application/x-www-form-urlencoded";
            // set the length of the content
            request.ContentLength = bytes.Length;

            // set up the stream
            Stream reqStream = request.GetRequestStream();
            // write to the stream
            reqStream.Write(bytes, 0, bytes.Length);
            // close the stream
            reqStream.Close();

            // Let's get the Response from Twitter
            var webresp = request.GetResponse();
            // Let's read the Response
            var sread = new StreamReader( webresp.GetResponseStream() );

            // Use SqlContext to return data to the QueryAnalyzer results window
            SqlContext.Pipe.Send( sread.ReadToEnd() );

        }
        catch (Exception exc)
        {
            // send error back
            SqlContext.Pipe.Send(exc.Message);
        }
    }
}

Here’s the app.config for this assembly.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.web>
    <trust level="Full" processRequestInApplicationTrust="true" originUrl="" />
  </system.web>
</configuration>

Once you build this project, you should have your assembly ( tweetsproc.dll ) which will be used by your CLR Sproc. Now it’s time to do some SQL server work.

Enable CLR access for SQL server

EXEC sp_configure @configname = 'clr enabled', @configvalue = 1
RECONFIGURE WITH OVERRIDE
GO

Create the SQL Assembly

CREATE ASSEMBLY tweetsproc_clr_assembly from 'C:\Users\eric\Desktop\blog\tweetsproc.dll'
WITH PERMISSION_SET = EXTERNAL_ACCESS
GO

Create your SPROC

CREATE PROC tweetsproc_tweet(	@username as nvarchar(50),
								@password as nvarchar(50),
								@tweet as nvarchar(140)
							)
AS
	-- [Assembly Name].[Class Name].[CLR function Name]
	EXTERNAL NAME tweetsproc_clr_assembly.tweetsproc.PostTweet
GO

Tweet from a sproc

EXEC tweetsproc_tweet 'TwitterUsername', 'TwitterPassword', 'Hey @ericfickes, I''m tweeting from my database too!'

Running this sproc returns the XML response from Twitter.

Tweetsproc returns the full Twitter response

That’s one sample CLR SPROC in the bank!  Feel free to download this code and try it out yourself.  I’d love to get some feedback on anybody looking to use this for real.  While tweeting from a stored procedure probably isn’t a hot topic for anybody, this is a nice teaser for what you can do with CLR sprocs now.

Download code here.

Inside this zip you’ll find this.

• install.sql is everything you need to install this on your database
• tweetsproc.dll is the twitter assembly used by the sproc
• tweetsproc folder is the .net class library project

Everything you need to get TWEETING from a sproc

Visual Studio 2008's Publish Failed message

Here’s what you should do inside of Visual Studio to find out why your publish failed.

1. Click the Tools menu > then Options to bring up the Options dialog.
2. Expand ‘Projects and Solutions’ on the left and click General
3. On General, click ‘Show Output window when build starts’
4. Now click on ‘Build and Run’ in the left tree
5. Next select a value from the ‘MSBuild project build output verbosity’ drop down menu
6. OK your way back to the main Visual Studio window
7. The next time you Build or Publish your project, you should see the Output panel pop up.  If your publish is still failing, the answer will live inside the Output panel

Here’s a visual walkthrough of these instructions.

Tools > Options > Projects and Solutions > General

Tools > Options > Projects and Solutions > Build and Run

Visual Studio's Output Panel

<%# Container.ItemIndex+1 %>

And if you want to get the number of records in your DataBound control, do this

<%# YourControlId.Items.Count %>

Where YourControlId is the id of your DataBound control, such as an ASP:Repeater