由于连接已断开，无法完成请求的操作

Question

这段代码有什么问题，我该如何解决？

我使用的是.net 3.5，Sql Server 2008 Express版本是Windows 7 64。 我收到了这个错误：

[UpdateFileStatus]错误 -
System.InvalidOperationException：无法完成请求的操作，因为连接已断开。    at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransaction（TransactionRequest transactionRequest，String name，IsolationLevel iso，SqlInternalTransaction internalTransaction，Boolean isDelegateControlRequest）    在System.Data.SqlClient.SqlDelegatedTransaction.Initialize（）    在System.Transactions.TransactionStatePSPEOperation.PSPEInitialize（InternalTransaction tx，IPromotableSinglePhaseNotification promotableSinglePhaseNotification）    在System.Transactions.TransactionStateActive.EnlistPromotableSinglePhase（InternalTransaction tx，IPromotableSinglePhaseNotification promotableSinglePhaseNotification，Transaction atomicTransaction）    在System.Transactions.Transaction.EnlistPromotableSinglePhase（IPromotableSinglePhaseNotification promotableSinglePhaseNotification）    在System.Data.SqlClient.SqlInternalConnection.EnlistNonNull（Transaction tx）    在System.Data.SqlClient.SqlInternalConnection.Enlist（Transaction tx）    在System.Data.SqlClient.SqlInternalConnection.EnlistTransaction（事务事务）    在System.Data.SqlClient.SqlConnection.EnlistTransaction（事务事务）    在System.Data.Linq.SqlClient.SqlConnectionManager.UseConnection（IConnectionUser用户）    在System.Data.Linq.SqlClient.SqlProvider.get_IsSqlCe（）    在System.Data.Linq.SqlClient.SqlProvider.InitializeProviderMode（）    at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute（Expression query）    在System.Data.Linq.Table 1.System.Linq.IQueryProvider.Execute[TResult](Expression expression) at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable 1源，表达式`1谓词）    在StorageQuest.Ovm.Connection.Dal.FilesDal.GetFile（Guid fileId，Int32 fileFolderId，Int32 fileFolderFileId，Int16 fileVersion）    在StorageQuest.Ovm.Connection.Dal.FilesDal.UpdateFileStatus（Guid fileId，Int32 fileFolderId，Int32 fileFolderFileId，Int16 fileVersion，Guid discId，FileStatus fileStatus）    在StorageQuest.Ovm.Connection.Bll.FilesBll.UpdateFileStatus（Guid fileId，Int32 fileFolderId，Int32 fileFolderFileId，Int16 fileVresion，Guid discId，FileStatus fileStatus）

        public bool UpdateFileStatus(Guid fileId, int fileFolderId, int fileFolderFileId, short fileVresion, Guid discId, FileStatus fileStatus)
    {
        FilesDal filesDAL = new FilesDal(this.connection);

        try
        {
            using (TransactionScope transcope = new TransactionScope(TransactionScopeOption.Required, TimeSpan.Zero ))
            {
                bool result = filesDAL.UpdateFileStatus(fileId, fileFolderId, fileFolderFileId, fileVresion, discId, fileStatus);
                transcope.Complete();
                return result;
            }
        }
        catch (Exception ex)
        {
            SqlConn.LogConnection.Error(null, ex);
        }

        return false;
    }

        internal bool UpdateFileStatus(Guid fileId, int fileFolderId, int fileFolderFileId, short fileVersion, Guid discId, FileStatus fileStatus)
    {
        File file = null;

        try
        {
            file = GetFile(fileId, fileFolderId, fileFolderFileId, fileVersion);
        }
        catch (Exception ex)
        {
            SqlConn.LogConnection.Error(null, ex);
        }

        if (file == null)
            return false;

        file.FileDiscID = discId;
        file.FileStatus = (byte)fileStatus;

        try
        {
            return SaveFile(file);
        }
        catch (Exception ex)
        {
            SqlConn.LogConnection.Error(null, ex);
        }

        return false;
    }

        internal File GetFile(Guid fileId, int fileFolderId, int fileFolderFileId, short fileVersion)
    {
        using (FilesDataContext fileDC = new FilesDataContext(this.connection)
            {
                DeferredLoadingEnabled = false,
                CommandTimeout = 0
            })

            return fileDC.Files.FirstOrDefault(
                    f => f.FileID.Equals(fileId) &&
                         f.FileFolderID.Equals(fileFolderId) &&
                         f.FileFolderFileID.Equals(fileFolderFileId) &&
                         f.FileVersion.Equals(fileVersion)
                            );
    }

        internal bool SaveFile(File file)
    {
        ChangeSet changeSet = null;
        int changeCount = 0;

        using (FilesDataContext fileDC = new FilesDataContext(this.connection)
            {
                DeferredLoadingEnabled = false,
                CommandTimeout = 0
            })
        {
            if (file.FileRowVersion == null)  //insert a file
            {
                fileDC.Files.InsertOnSubmit(file);
                changeSet = fileDC.GetChangeSet();
                changeCount = changeSet.Inserts.Count;
            }
            else                              //updates a file
            {
                fileDC.Files.Attach(file, true);
                changeSet = fileDC.GetChangeSet();
                changeCount = changeSet.Updates.Count;
            }

            try
            {
                fileDC.SubmitChanges();
            }
            catch (ChangeConflictException cce)
            {
                fileDC.Log = Console.Out;
                Console.WriteLine(cce);
                SqlConn.LogConnection.Error(null, cce);
                //SqlConn.ChangeConflictException(fileDC);
                return false;
            }
            catch (InvalidOperationException ioe)
            {
                SqlConn.LogConnection.Error(null, ioe);
                return false;
            }
            catch (Exception ex)
            {
                SqlConn.LogConnection.Error(null, ex);
                return false;
            }
        }

        return !changeCount.Equals(0) ? true : false;
    }

提前谢谢。