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Showing posts from January, 2008

Seattle Code Camp: Kick Your Hash

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This was Wayne Berry 's presentation about real-world crypto coding for web sites. The presentation was identical to his asp.net user group presentation. He stayed calm with 15 minutes of Digipen equipment not working and two room switches. But it was a great presentation and the level of detail and code was just right. He said he will post the presentation here at some point.

Seattle Code Camp: Advanced Query and Modeling Capabilities with Entity Framework

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This presentation was given by Zlatko Michailov & Asad Khan, PMs, Microsoft ADO.NET. The best thing said in the entire presentation was that if your model is well built you shouldn't have to do any group bys or joins. Drink the kool-aid, swallow the pill, enjoy that illusion in a real-world situation. Especially some piece of $%^@ database that is mission critical and the data is 10 years old, not normalized, and some one else's baby. But if you are going to dream, dream big, right? Their blogs can be found at: http://blogs.msdn.com/esql/ . E for entity. Why be normal? right?    

Seattle Code Camp: Top Open Source .NET Tools

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Rod Paddack gave this session wearing a great geek shirt. His enthusiasm for open source was reciprocated by many in the audience. Here is the list: SharpZibLib Compression Library PDFSharp.com creates PDF files CruiseControl continuous build system - never upset a build master Nant another build tool NUnit a developer's unit test framework NHibernate - persisting plain .NET objects to and from an underlying relational database DotNetNuke - mega portal system in VB.net AJAX Asp.Net ToolKit - very cool AJAX controls Ghengis - don't know what it really does but the website has other interesting tools MySQL - not sure how open source this really is ConnectionStrings.com - this one I need CodePlex.com - open source code repository Thoughtworks.com - lots of stuff Microsoft Patterns and Practices - cool stuff Code.MSDN.COM - for small bits of code snippets instead of the big stuff at codeplex Mentions during session included http://code.google.com/ ...

Did Someone Forget A WHERE Clause?

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Charter Communications officials believe a software error during routine maintenance caused the company to delete the contents of 14,000 customer e-mail accounts. http://www.foxnews.com/story/0,2933,325338,00.html I am glad today that I didn't do this and force my company to give a $50 credit to each customer.  Ouch. {6230289B-5BEE-409e-932A-2F01FA407A92}

Seattle Code Camp: Entity Framework Essentials

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From https://seattle.codecamp.us/   Jonathan Carter, Microsoft Developer Evangelist, gave an introductory talk about the Entity Framework which has just had a Community Preview release. It is basically a middle layer framework driven by Domain Driven Design for creating and extending objects on top of a data source. The data source presented was SQL Server but you could imagine all sorts of layers. There are two parts, the Entity Model and the framework for asp.net. A simple but nowhere complete comparison could be drawn to CodeSmith. Open Visual Studio, create a "file". You are asked for a data source and data objects to include. The framework displays an Entity Relationship diagram which you can dink with to create the objects the way they will work for the upstream code and not the downstream DB. While the presentation was a tad buggy, the framework looks like it is going someplace cool. The best part was the intellisense to your objects you just created via the fra...

Seattle Code Camp 2008 at Digipen

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Wayne, Rusty, Andy, and I went to code camp yesterday. The speakers were good, and there was a lot of code. I focused on the asp.net and core .net sessions. I attended two talks on Entity Framework, one on top 10 open source .net tools, one on crypography given by Wayne, and one on xUnit. By far the most interesting one was the xUnit discussion with it's dev team. I'll give sessions reviews and related links in the following days.  

The Beauty of LINQ

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I was recently working with an RDP settings file and its myriad of settings and corresponding lines. I couldn’t find what I needed so I thought it would be nice to sort the lines. I am sure there are utilities out there that can quickly sort a bunch of text lines but like most programmers, I thought it best that I develop my own solution. So I fired up VS and created a new Windows Forms project, added a standard TextBox and Button control to my form and wired up the following OnClick event: private void ButtonSort_Click( object sender, EventArgs e) {     TextBoxMain.Lines = TextBoxMain.Lines         .OrderBy(s => s)         .ToArray(); } Just too simple. Man I love LINQ!

What is {6230289B-5BEE-409e-932A-2F01FA407A92}?

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I have been adding {6230289B-5BEE-409e-932A-2F01FA407A92} at the bottom of my posts.  What posts you ask?  Well every post I am doing on the internet.  MSDN Managed Newsgroup forms, woodworking forums, and this blog are just some of the places.  Why you ask?  Well I want to be able to find all my posts that are unique to me.  It just so happens I share my name with several other people on the Internet so I wanted a unique name that was anonymous that would find only my stuff.  I will be adding to my BIOs when I write articles, and my web sites.  This way I can go to Google and search for my GUID and find everthing on the Internet that I have done.  You can do the same, just generate yourself a GUID at: http://www.guidgen.com/  and get started. {6230289B-5BEE-409e-932A-2F01FA407A92}  

Seattle Code Camp

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Will be presenting at the Seattle Code Camp https://seattle.codecamp.us/  this Saturday.  My talk is entitled "Kick Your Hash" and I will attempt to bridge the cryptography gap between code and theory by showing SQL Server and .NET code, real life examples, and practical correct uses for Hashing. Example 1: SELECT HashBytes( 'MD5' , 'password' ) SELECT HashBytes( 'MD5' , CONVERT ( varchar ( max ), 'password' )) SELECT HashBytes( 'MD5' , CONVERT ( nvarchar ( max ), 'password' )) Example 2a: ALTER PROC CheckLogin @Login varchar (50), @Password varchar (50), @Valid bit OUTPUT AS SET NOCOUNT ON SELECT * FROM [ User ] WHERE @Login = [ User ].[Login] AND [ User ].Hash =     HashBytes( 'MD5' , CONVERT ( varchar ( max ),[ User ].Prefix) + @Password) IF ( @@ROWCOUNT >0)      SET @Valid = 1 ELSE      SET @Valid = 0 Example 2b: CREATE TABLE [dbo].[User](     [UserId] [uniqueide...

When Is null not true?

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In C# we can have nullable types, like this: Boolean? isValid; Which means that isValid can be true, null, or false.  It is like a three way switch.  I use it to represent a bit field in SQL Server that can have a null value.  For example I might have this table: CREATE TABLE Account (IsValid bit ) Which creates me a table with a bit column that can be NULL.  I usually don't like to do this -- in fact I never do, however I am working with some people that don't bother to check the NOT NULL when they use the designer so I have to deal with it in my C# code.  So I ask the table designer what NULL means in the IsValid coulmn and he tells me it means false (not valid). So I query the database and set the result to isValid, in the C# class above.  So now I need to check to see if the account is valid.  It might seem like this would work: if (isValid) {...} However, that throws a compiler error, becuase you can't have Nullable type defa...

#1 Faster Coding

I was reading this article from a http://www.digg.com link (sorry I lost the link to the article) about how to be a faster developer and at the top of the list is becoming very good at your editor.  The author pointed out that the hot keys (the ability to navigate and execute commands without using your mouse) where essential.  I agree with him, the more you have to move your mouse the less you can type and it is a real waste of time going between the mouse and the keyboard.  However, he was ranting about EMACS and of course the Windows programmer's editor of choice is Visual Studio. My favorite hot keys right now in Visual Studio: Ctrl K-D : To reformat the code.  Type whatever I want, not tabs, no enter. Ctrl K-D and it is formatted correctly. Ctrl M-O : To collapse all the regions.  Finish a bug fix, Ctrl M-O to collapse, Run Unit Test, Handle Exception in Code (automatically expands) and ignore all the collapsed code. Ctrl F : For Quick F...

Yet Another Interview Question

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"When you program by yourself do you use source control?" What I want to hear is that they use source control.  Source control -- even by yourself -- is an important tool that helps you backtrack out of coding tangents that fail.  Hosted on another server it is a valuable form of backup off your own box.  It also shows that the person has programmed in a shop where source control was enforced (rightfully so) and understand how it beneficial it is.  

Clearing My Inbox

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Another programming tip in the article I read was to keep a task list for the work left in your programming project and work off it.  Most projects are so large that you can't keep track of all the loose ends.  I have never had trouble keeping track of the loose ends of a project when my head is in it -- however I know the day is coming soon. Being a former Microsoft employee and Microsoft being an email culture (at least when I was there in 1997), I use my Inbox to keep track of all my tasks.  Ten years ago it was around 200 emails -- all that needed action.   I was alright with that since I got 100-400 emails a day I was keeping them under 200 and everything was good.  About 5 years ago the inbox topped 300 emails and I was still alright with that -- keeping them paired down and knowing I would never clear it completely -- remember all 300 required action.  At the end of 2007 I had 400 emails in the inbox and I knew there was a problem -- so I set a...

Control.ClientID Extremely Useful for Creating Client-Side Functionality

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The ClientID property is my favorite property this week and will definitely reshape how I write asynchronous functionality in the future.  I learned about this while adding some functionality to a client's site earlier this week.  The original site was created off-shore and people like me are the ones who get to take care of it.  It's been fun so far and had I not been working on this site this week I would've totally overlooked this wonderful property. First off, ClientID is a readonly property (as it should be!) that does nothing more than get you the id of the control that is rendered.  Take the following rendered RequiredFieldValidator . <span id="datalistContent_ctl05_requiredDescription" style="color:Red;visibility:hidden;">I saw what you did there.</span>  Not quite the same as my original "requiredDescription" ID set in the .aspx.  When this control was processed this original ID was appended to the UniqueID created for...

Source Control Pet Peeves

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There is no reason, NONE WHATSOEVER , for updating SVN (or any other source code repository) with code that does not compile.  There are 2 rules for version control that are both #1: 1. Check code in frequently 1. Don't check projects in unless they compile Some argue that this isn't a good practice (1 #2 above) but let me explain.  Let's say you are working on a distributed team and there are 3 people working on a project.  Team members 1 & 2 are working on a class library for a web project.  They figure they are done for the day and check in the code that they worked on. Team member 3 (me) wants to check out this class library when working on a new & unrelated project. I add this library to my project, do my thing, build. WTF? 57 Errors and 2 warnings.  I should see 0 Errors and 2 warnings.  Warnings are usually harmless and a lot that I have seen lately stem from converting 1.x websites to 2.0, 3.5 projects and usually have...

Side by Side Databases

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Let's say you forgot a WHERE clause and want to restore your backup database to recover the lost data.  However, you don't want to override the data that has accumulated since the last back-up.  What you need to do is restore the backup along side the newer database.  Here is how to do it: RESTORE DATABASE backup    FROM 'C:\temp\lastbackup.bak'    WITH MOVE 'mydb_Data' TO 'C:\MySQLServer\backupdb.mdf',    MOVE 'mydb_Log' TO 'C:\MySQLServer\backupdb.ldf'; This statement tells the SQL server to create a database called "backup", from the lastbackup.bak file and not to use the files stored in the back-up, but instead use: backupdb.mdf and backupdb.ldf.  Unless you remap your backup files, the RESTORE will try to override the old files that are in use by the newer database -- which will cause a SQL Server error (not data loss). {6230289B-5BEE-409e-932A-2F01FA407A92}

System.ArgumentException: An item with the same key has already been added

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Intermitently my code was getting this Exception: "System.ArgumentException: An item with the same key has already been added."  The code looked like this: if (!_roleTypeNameDict.ContainsKey(roleTypeName)) _roleTypeNameDict.Add(roleTypeName, ...) Since I have done a lot of C++ programming right away I realized that I had a threading issue, however the question was why? It just so happens this was a static method, calling a static property, which means that more then one thread might be accessing _ roleTypeNameDict at a time: private static Dictionary<String, RoleTypes> _roleTypeNameDict    = new Dictionary< string , RoleTypes>(); public static RoleTypes FindCachedRoleTypesFromRoleTypeName(String roleTypeName) { if (!_roleTypeNameDict.ContainsKey(roleTypeName))        _roleTypeNameDict.Add(roleTypeName, ...); ... } To solve the issue you need to create a lock to protect the check to add from the add like this: priv...

TreeView Control with Ajax Slide Show

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Just finished a little app to have a treeview control the file system navigation for images to be displayed in the AJAX Slide Show provided in the Microsoft AJAX Control toolkit. A www.15seconds.com articles about the application will be posted soon.

Just so you know...

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Detaching a database in SQL Server doesn't delete the files (.ldf, .mdf, .ndf) where the data is stored.  Deleting a database is different then detaching a database.  Detaching allows you to move the files and reattach them to a different SQL Server.  However, once you detach a database it is not available to query. {6230289B-5BEE-409e-932A-2F01FA407A92}

Interview Question #3

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My brother called, he had forgotten a WHERE clause and had lost some data.  I felt really bad for him -- the kind of sinking feeling you get when someone you know has a death in the family.  I can relate -- I have forgotten a few WHERE clauses in the past couple of years.  Right after he called I checked my database backups to make sure they where still running every night. This reminded me of one of my favorite interview questions: "Tell me about the last time you forgot a WHERE clause?"  I am looking for that sinking recognition that takes place when someone knows the question and can relate.  And if they have never forgotten a WHERE clause -- I just know they haven't programmed much T-SQL, cause we all do it from time to time.  I also want to hear how they recovered their data and what they are doing differently to prevent the problem.  A developer I know at work always writes the WHERE clause before he writes the DELETE or UPDATE line ju...

Use T-SQL's NULLIF To Fix Divide By Zero Errors

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Lately I have doing a lot of SSRS and overall SQL work for a project.  In returning some data to process server-side my data retrieval method was returning null * which means that an exception was thrown. I did a little digging around and then decided to execute the stored procedure manually (i.e. Management Studio).  After debugging in Visual Studio and seeing what the values were and that they were in fact getting passed to the stored procedure I used the same signature to execute the proc in Management Studio.  Hmm, no dice.   My error message was of a "Divide-By-Zero" fashion.  This is the first time that I have ever seen this.  A little reading on the subject and I come to find out that the field used as the denominator allowed nulls. Enter NULLIF . This is what saved the day.  This function will compare two values and return a null value if the expressions are equal.  For example, take the following dummy stored procedure. CREATE...

Generic Session Wrapper Class for Session Object Maintenance

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I've been reading a couple of renditions of this SessionWrapper class via DotNetKicks over the past couple of days.  While I must admit that this code isn't 100% original, I can say that I have given it a more generic feel and added a little bit of functionality.  With my implementation you can not only use any class, you can specify a name for the session object.  That way if you want to store say the Account and Order objects in Session you could use the same method without creating a wrapper for each type. using System.Web; namespace NamespaceNameGoesHere {     public class Session <T> where T: class     {        private string _name = string .Empty;       public string Name       {           get { return _name; }           set { _name = va...

Converting Legacy Tables From Int Primary Keys To UniqueIdentifiers

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If you have some legacy tables you where you want to convert from having a primary key of int to a primary key of uniqueidentifier, you need to do a lot of work.  Here are the steps: 1) Drop all forigen keys contraints that points to the table being modified. 2) Drop all views that reference the table being modified. 3) Drop all indexes that use the primary key or any forigen key column that points to the table being modified. 4) Rename all the old forigen key column that points to the table being modified, so that we can add a new column with the original name of type uniqueidentifier. 5) Drop the primary key contraints on the table being modified. 6) Add a new forigen key column to all tables where there was a forigen key column that points to the table being modified of the same name with a type of uniqueidentifier.  Make then NULL 7) Rename the primary key of the table being modified -- the int column. 8) Add a new column with the original primary key name of type ...

Starting to Use GUIDS in SQL

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When you start to use GUIDs (uniqueidentifiers) as primary keys in T-SQL one of the first questions is how to replace @@IDENITY in your primary key column.  A typical table with int as a primary key might look like this: CREATE T1(ID int PRIMARY KEY IDENTITY , Name varchar (50)) When you insert into this table and want the primary key of the row that you inserted you typically do this: DECLARE @ID int INSERT INTO T1 (Name) values ( 'Tom Smith' ) SET @ID = @@IDENTITY However, when you use uniqueidentifiers as primary keys you don't declare them as IDENTITY, here is how you would build this table: CREATE T1(ID uniqueidentifier PRIMARY KEY , Name varchar (50)) And here is what the INSERT looks like: DECLARE @Id uniqueidentifier SET @Id = NewId () INSERT INTO T1 (ID, Name) VALUES (@Id, 'Tom Smith' ) When using uniqueidentifiers you create them ahead of the insertion and SQL Server doesn't keep track of the process for you. {6230289B-5BEE...

I Just Finished My First VB.NET Project in Over 2 Years

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I just finished my first VB.NET project and it was pretty interesting. Some of you might be wondering why I did a project in VB.NET.  There are actually 3 reasons: Client's money is still green Site was the first .NET application by someone straight out of classic ASP Client won't pay to upgrade to C# Now that we've cleared that up, I'd like to say how awkward it was.  First of all, it took me probably twice as long to write this as it would if it were in C#.  This is due to my not knowing the in's and out's of VB.NET 2.0 and not necessarily something I can blame on VB.  While there are some great additions to VB.NET such as Generics (even though the syntax isn't very intuitive), the  Using construct (about time!) there is one feature that is still not there that I use day-to-day when writing applications in C#. I am talking about collapsible regions within methods. Take the following code example: Protected Sub ButtonClick( ByVal sender As ...

T-SQL Performance With INNER JOINs

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Lets take a quick look at INNER JOINs in T-SQL.  This select statement is a very typical: SELECT * FROM Products INNER JOIN Category ON Products.CategoryId = Category.CategoryId WHERE Products.AccountId = @AccountId However, it can be rewritten to be much faster: SELECT * FROM Category INNER ON Products JOIN Products.CategoryId = Category.CategoryId AND       Products.AccountId = @AccountId Here is why: In the first statement all the rows in the products table are being joined to all the rows in the category table, producing a bigger table, that is then walked to find the correct account.  This might make a very large table after the join if there are many accounts and the category table is very wide.  SQL Server has to deal with this large in query table being produced.  However, in the second statement only the products that are in the required account are joined to the category table -- significantly reducing the j...

Another Interview Question

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One question I ask when interviewing is what types of T-SQL statements are the worst for performance, I am looking for answers like the below (not in any order): Cursors IN clauses Large INNER JOINs What this tells me about the person is that they are conscience of the code impact they have on the server.  Someone that doesn't know the answer will write anything that works just to get their job done -- which means that I will later have to clean-up their stuff. {6230289B-5BEE-409e-932A-2F01FA407A92}

Removing Duplicate Rows In T-SQL

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Been doing some interviewing lately and finding that people think they are really good at T-SQL (claiming they are a 6 out of 10), however almost none of them write their T-SQL by hand.  If you are using the WYSIWYG query builder you are a 3 out of 10, or less.  Here is one of my favorite interview problems that comes up in real life (my life) a lot. Given a table like this: CREATE T1 (ID int PRIMARY KEY , Name varchar (50)) That has duplicate rows in the name column, write a query to "clean" the duplicates leaving only on row per name.  So if "Tom Smith" shows up in two rows (ID: 2, and 4), the query would delete either rows with ID 2 or 4 and leave the other one.  My favorite answer is: DELETE T1 WHERE NOT T1.ID IN ( SELECT MIN (T1.ID) FROM T1 GROUP BY Name) This includes an IN clause where is terrible for performance -- however the best solution I know.  Most people try it with a cursor which is much harder. Note:  This is how yo...

MSDN Managed Newsgroups

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MSDN Managed Newsgroups might be one of Microsoft's best kept secrets for development resources.  If you have an MSDN subscription you can post a development question on the Managed Newsgroups and a Microsoft support person will answer it within 24 hours.  For me this is an invaluable resource -- much easier then calling on the phone.  You can also post as many times as you like.  There are a few hoops to jump through to tie your MSDN subscription to your passport login, which take about 10-15 minutes to figure out.  If you don't have a MSDN subscription getting help is hit and miss - Sometimes you get a response and sometimes it is correct. Too bad all their products are not supported this way. http://msdn2.microsoft.com/en-us/subscriptions/aa974230.aspx {6230289B-5BEE-409e-932A-2F01FA407A92}

TreeView.FindNode returns null when PathSeparator is not set

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I'm writing a web app that connects a treeview control with a ajax slide show. Tons of feature creap but what is new. I don't get a chance to program as often as I would like so when problems pop up like FindNode returning null on a valid ValuePath, I assume it's me, my programming, my install, my whatever. I look at the docs, I look at sample code. I even look for other people having the problem but I don't see any solutions but others definitely having the problem. In one forum, the poster mentions that he figured out his path separator can't be a symbol in the valuepath. Hmmm. If you don't set the PathSeparator, it defaults to "/" which is the same thing as the directory structure I'm using in the valuepath. So problem is solved when I explicitly set the PathSeparator to "|". -Dina          

Hierarchical Structure

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Still working on treeview with ajax slide show. I had to write 2 expandnode functions: one based on file system ("/dir/dir1/dir2") and one based on treeview with PathSeparator as "|" ("/dir/|/dir/dir1/|/dir/dir1/dir2/"). This is so that the currently selected node (ie directory) can be expanded and highlighted regardless if the web page is opening for first time, on postback, on querystring, etc. It should be as easy as filling in a datatable-ish structure where the structure automatically resolved down the hierarchy based on a given path. But I can't figure out how to get two very similar structure into a single container without doing alot of work myself. If you know where I'm going wrong - let me know. -Dina    

SQL Server Hole #1

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In my opinion SQL Server 2005 is full of holes, and my definition is functionality that is available doesn't span the whole gamete of the server.  For example, aggregates don't work with GUIDs (call uniqueidentifiers in SQL).  Here is non-working code that I would like to see work: CREATE #Temp(Id uniqueidentifier , Name varchar (50)) SELECT MAX (Id) FROM #Temp DROP TABLE #Temp Why doesn't this work?  GUIDs are just 128-bit numbers, they are all unique and one comes before the other, there should be a MAX and MIN.  This does work: CREATE #Temp(Id uniqueidentifier , Name varchar (50)) SELECT MAX ( CONVERT ( varchar (41),Id)) FROM #Temp DROP TABLE #Temp However, I don't want the extra overhead of converting each GUID to a String.