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Posted 9 Aug 2007

Execute .NET Code under SQL Server 2005

, 26 Aug 2007
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Article describes all the problems and constraints defined to use managed code under SQL Server 2005.


First of all, I would like to congratulate the Microsoft Development Team for their superb and innovative technology using which we can use managed code written in any of the .NET supported languages in Microsoft SQL Server 2005 Stored Procedures. If I make it simple, then "Now you can call any function written in .NET class library in your SQL Server stored procedure". This technology will allow us to use the features of .NET language with the extendibility of SQL Server.


I got an article of using MSMQ from SQL Server in CodeProject written by a gentlemen regarding MSMQ, and Messaging was used from SQL SP. I tried to show the constraints and limitations of using such assemblies and the required configuration in SQL Server 2005, so that the developers can begin. And I am sharing the practical problems which I faced in the actual implementation of this.

Before starting, you have to enable the managed code execution feature of the SQL Server which is disabled by default. To enable it, execute the following code as a query in your SQL Server query editor.

sp_configure 'clr enable', 1

Now your server is ready to run managed code under its runtime. But let me tell you it's not magic but it's the same technology being used by the .NET framework. The only important part is that now SQL Server is also able to execute code on CLR. Isn't it great? Before writing this article, I did a lot of research on this. I got several articles explaining the same. But I faced a lot of problems because things were scattered. Now I am trying to simulate the whole procedure in this article. I did this study because of my specific requirements. I was using Message Queuing Service of Microsoft in C# .NET. But after some time, I got a requirement in which I needed to send a message from a Stored Procedure to MSMQ Queue. And till that time for me it was possible by using the System. Messaging namespace of .NET runtime only. I know most of the developers are wondering about MSMQ. Don't worry, I won't go into details of that right now. We will start with a simple application which will use a simple string returning function of C# .NET class library. Let's start with the class library.

  • Start .NET 2005 Studio.
  • Open a new class library.
  • Select C# as the language.
  • Name the project as ManagedCodeAndSQLServer.
  • By default, you will find a class named Class1.cs created for you.
  • Rename it as BaseFunctionClass.cs.

Create a simple function in the class as follows:

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Data.SqlTypes;
using System.Data.SqlClient;
using Microsoft.SqlServer.Server;

namespace ManagedCodeAndSQLServer
    public class BaseFunctionClass
        #region "Default Constructor"
        public BaseFunctionClass()

        #region "Welcome Function"
        /// <summary>
        /// This function will be called from the SQL Stored Procedure.
        /// </summary>
        /// <param name=""strName"">Name</param>
        /// <returns>Welcome Message</returns>
        public static void GetMessage(SqlString strName, out SqlString  
          strMessge = "Welcome," + strName + ", " + "your code is getting
          executed under CLR !";


Important Points

I hope you are able to notice some new things in the above code. First of all, the [SqlProcedure] attribute on the GetMessage function intimates the CLR that the function is callable from SQL Server Stored procedure. The things that I am telling you are my own experiences; you may not find these things in articles published on the Internet. When using a CLR function, you must remember that the SQL server nvarchar is equivalent to System.String. But the most important part is that "CLR enabled procedure can only return Int32, Int and void data types". That's why I have used output parameter with the GetMessage function. Also I have used SqlString instead of System.String. Please keep all the above things in mind.

Now build the project and leave it because your work from the .NET class library point of view is over. Now come to your SQL Server again. I hope you still remember that we enabled CLR integration in our server at the start of the article. If not, then don't wait for me to come and enable it.

We have to register ManagedCodeAndSQLServer.dll as an assembly in our database. To register the assembly, you should have owner rights in your database or you should be the local system admin or Server Admin. The assemblies that we are going to register should be registered in UnSafe mode. Otherwise they would not be able to access resources external to SQL Server 2005. And to register an unsafe assembly, you should have 'unsafe' rights enabled in your username or role. All the above things are very important so take care of them, otherwise you won't be able to register your assembly. So create a database 'TestingCLR'. Before registering the .NET assembly in the database, you have to set the trustworthy option of the database on using the following code:


Now register ManagedCodeAndSQLServer.dll under that using the following code:

FROM 'E:\Important\SQL\ManagedCodeAndSQLServer\ManagedCodeAndSQLServer\bin\

I am again saying if the dbo is not having 'unsafe assembly' right, it won't work. Similarly if I am using a specific class of .NET in my DLL, I have to register it prior to DLL registration in the same way. For example, I am using System.Messaging in my assembly, then I have to register it using the following code:

FROM 'C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Messaging.dll'

To use the normal functionality, we need not register the DLL from .NET runtime as in our case. Now in your server explorer, go to your TestingCLR database, select Programmability and in Assemblies, you will find an assembly registered with the name given by you, i.e., "HelloDotNet". Now you are almost done. You should know the full path (namespace convention) of the function that you are going to use from that assembly. In our case, it is: ManagedCodeAndSQLServer.BaseFunctionClass and GetMessage is our function to be used. Now I am creating a simple Stored Procedure to use this assembly as follows:

CREATE PROCEDURE usp_UseHelloDotNetAssembly
@name nvarchar(200),
@msg nvarchar(MAX)OUTPUT
AS EXTERNAL NAME ManagedCodeAndSQLServer.[ManagedCodeAndSQLServer.

To execute the procedure:

DECLARE @msg varchar(MAX)
EXEC usp_UseHelloDotNetAssembly 'Kittu And Tannu',@msg output
PRINT @msg

You will get the following output: Welcome, Kittu And Tannu, your code is getting executed under CLR !

Try it and enjoy!


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Kamal Singh Kharayat
Technical Lead Government of Dubai
United Arab Emirates United Arab Emirates
Thank you for visiting my profile at Code Project.

I have a proven track record of delivering excellence in working on many technically challenging project across the organizations I have had worked with. My core competencies are SharePoint Development, Administration, ASP.NET, .NET MVC, SQL Server.

Adding great values to the project and team is what I work for. I believe we should deliver the best possible solutions to the customer without compromising best practices and recommendations. Also for a better project management we need to juggle things like time, cost, risk, and quality and customer satisfaction in a successful project delivery.

Specialties: Competent technologist in the field of Microsoft .NET and SharePoint Technologies.
“A successful application development always leads to Feasibility, Reliability, Scalability and more importantly a better usability.”

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"Improvement is the only thing which makes me happy...."
e-mail Addresses:
skype id: stek_ks

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Comments and Discussions

Generalnice artical Pin
mhemal2-Sep-07 18:37
membermhemal2-Sep-07 18:37 
GeneralEnable CLR Pin
kurisutofuJP26-Aug-07 15:27
memberkurisutofuJP26-Aug-07 15:27 
QuestionError in naming? Pin
kurisutofuJP26-Aug-07 15:22
memberkurisutofuJP26-Aug-07 15:22 
AnswerRe: Error in naming? Pin
Kamal Singh D. Kharayat26-Aug-07 18:24
memberKamal Singh D. Kharayat26-Aug-07 18:24 
GeneralRe: Error in naming? Pin
kurisutofuJP26-Aug-07 19:03
memberkurisutofuJP26-Aug-07 19:03 
GeneralThanx!! Had not known this functionality of SQL server... Pin
nishantsagar8317-Aug-07 22:32
membernishantsagar8317-Aug-07 22:32 
QuestionInteresting article but a few questions Pin
Jon Masters14-Aug-07 23:08
memberJon Masters14-Aug-07 23:08 
AnswerRe: Interesting article but a few questions Pin
Kamal Singh D. Kharayat15-Aug-07 20:29
memberKamal Singh D. Kharayat15-Aug-07 20:29 
Hi Jon, thanks for the appreciation. I would definitely like to read the article written by you on MSMQ from SQL Server, as I am sure it would be interesting and full of knowledge. I read one article on the said topic on code project from some other author and it was really very interesting. Here in my article I mainly focused on the problems and the constraints that developers will face while using this feature of SQL Server 2005. I never focused on MSMQ. Also I tried to make it simple and simulate things as you said.Smile | :)

I would like to reply your questions:

1.When you will register System.Messaging on SQL Server 2005, its all dependencies will get registered automatically, you need not register it explicitly. You can't get your desired objects of .net as return type from any registered dll as return type, as SQL Server has some limitation on the return type from the managed code. SQL Server can accept string and Int as return type from .net dll. You can receive body of your Message Object in form of string.

2.First of all if your application is using high Database operation then you should perform it in SP only and use .net code for complex calculation and to maintain the dependencies of your DB opreation which are on .net application. Because this feature is launched to skip frequent Server round trip of the Database for .net code. On the other hand the dll still running under CLR and all the complexity related to DLL are still handled by CLR and its services.

3.We need not to worry about the static CLR objects because still its the same process that was under normal .net class library. CLR and other services like garbage collection, memory management are still in place whether the assembly is getting called from other application written in .net or from SQL server 2005 Stored Procedure. So they are not under the mercy of SQL Server 2005.

4.I can't say whether the customer will move to SQL 2005 from SQL 2000 for this feature, but I must say if they are moving to SQL 2005 for a lot of other features (The question depends on your whole application) Smile | :) , we should use this feature where there are lots of Database operations. So that database operation can be handled on SP only and for complex code we can call dll from .net language.Smile | :)

Jon, I hope we are not the soldiers standing opposite sides of LOC. Anyways thanks for your valuable suggestion and views. I tried to answer you , please correct me if I am wrong.Smile | :)


Kamal Singh
(Software Engineer)

GeneralRe: Interesting article but a few questions Pin
Jon Masters15-Aug-07 23:01
memberJon Masters15-Aug-07 23:01 
GeneralRe: Interesting article but a few questions Pin
Kamal Singh D. Kharayat15-Aug-07 23:43
memberKamal Singh D. Kharayat15-Aug-07 23:43 
GeneralRe: Interesting article but a few questions Pin
Jon Masters16-Aug-07 0:08
memberJon Masters16-Aug-07 0:08 
GeneralExcellent!!!!!!!!!!!!!!! Pin
Rashmi Patel RJ14-Aug-07 3:06
memberRashmi Patel RJ14-Aug-07 3:06 
GeneralVery Help Full Pin
sneharahul14-Aug-07 1:55
membersneharahul14-Aug-07 1:55 
GeneralInteresting Pin
lallous13-Aug-07 21:37
memberlallous13-Aug-07 21:37 

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