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Editorial Team
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Asked: 2026-05-12T16:08:36+00:00

This is my first MVC/Linq to SQL Application. I’m using the out of the

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This is my first MVC/Linq to SQL Application. I’m using the out of the box SQL Membership with ASP.NET to track users through my system.

As most of you know, the UserId is a guid, great. However, to link other user-created tables in the system, I decided to go with username instead of userid. The reason I did this was because:

  1. Username is unique anyway
  2. It prevents me from having to make an extra call when handling db functions.

So for example: I don’t have to do a look up on the userid based on username to create a new story; I simply insert User.Identity.Name into the story table.

Now I did run into some nasty complication, which seems to be related to this. It worked fine on my local machine, but not on the host. I continually got an error that went something like this:

“System.InvalidCastException: Specified cast is not valid. at System.Data.Linq.IdentityManager.StandardIdentityManager.SingleKeyManager”…

This happened whenever an insert on the db occurred on the host. If I understand correctly, this is a bug currently that happens when you link a non integer field (in my case username) to another table of a non integer field (username in aspnet_user). Although the bug reported seems a little bit different, maybe they are similar?

https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=351358

In any case, MS bug or not – is storing the username instead of the userid in my tables a bad idea? If it is, why?

Update

I just wanted to add some more context here. A good point people are bringing up is that this is dangerous if I want to allow users to change their username in the future. Perfectly valid!

However, this application relies heavily on the username. Each user creates one and only one story. They then link to their story by using: mysite/username. Therefore, the application will never allow them to change their username. It would cause a potential nightmare for people who follow the link only to see it no longer exists.

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1 Answer

  1. Editorial Team

    Be careful regarding your comment regarding usernames are unique. The minute Anita Takeabath gets married to Seymour Butts suddenly atakebath wants to be abutts.

    Just a thought!

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