Default Values (of C# variables) Issue in LINQ to SQL Update

Question

I have the following code for updating Account table with LINQ to SQL. AccountNumber is the primary key column. The only value which need to be updated is AccountType; howev

Answer 1

I solved this issue by changing the update approach by following the answer in LINQ to SQL: Updating without Refresh when “UpdateCheck = Never”

UpdateCheck is set as Never for the Duration column

    public void UpdateAccount()
    {
        //Used value from previous select
        DateTime previousDateTime = new DateTime(2012, 6, 26, 11, 14, 15, 327);
        int prevDuration = 0;

        RepositoryLayer.Account accEntity = new RepositoryLayer.Account();
        accEntity.AccountNumber = 1; //Primary Key
        accEntity.ModifiedTime = previousDateTime; //Concurrency column
        //accEntity.Duration = prevDuration;

        accountRepository.UpdateChangesByAttach(accEntity);

        //Values to be modified after Attach
        accEntity.AccountType = "WIN-WIN";
        accEntity.ModifiedTime = DateTime.Now;

        try
        {
            accountRepository.SubmitChanges();
        }
        catch(System.Data.Linq.ChangeConflictException e)
        {
            throw new Exception(e.Message);
        }

    }


   public virtual void UpdateChangesByAttach(T entity)
    {

        if (Context.GetTable<T>().GetOriginalEntityState(entity) == null)
        {
            //If it is not already attached
            Context.GetTable<T>().Attach(entity);
        }

    }

Generated SQL

UPDATE [dbo].[Account]
SET [AccountType] = @p2, [ModifiedTime] = @p3
WHERE ([AccountNumber] = @p0) 
      AND ([ModifiedTime] = @p1)

-- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [1]
-- @p1: Input DateTime (Size = -1; Prec = 0; Scale = 0) [6/26/2012 11:14:15 AM]
-- @p2: Input NChar (Size = 10; Prec = 0; Scale = 0) [WIN-WIN]
-- @p3: Input DateTime (Size = -1; Prec = 0; Scale = 0) [6/26/2012 11:16:29 AM]

Answer 2

This should do:

int number = 4;
var acc1 = new accountRepository.Accounts.Where(a => a.Number == number).FirstOrDefault();

if (acc1 == null)
{
    // Not found by ID, create new
    acc1 = new RepositoryLayer.Account();
    acc1.Number = number;
    accountRepository.Accounts.AddObject(acc1);
}

acc1.AccountType = "Verify";

accountRepository.SubmitChanges();