使用transaction后，链接无法关闭

[sky-defender]

下面这段代码，使用transaction之前没有问题，但是使用transaction之后，无法将oleConnection关掉，为什么？

public static void OpenDB()
        {
            if (_oleConnection.State != ConnectionState.Open)
            {
                _oleConnection.Open();
            }
        }

        public static void CloseDB()
        {
            if (_oleConnection.State != ConnectionState.Closed)
            {
                _oleConnection.Close();
            }
        }


public static void SaveControl(List<SmartControlData> list)
        {
            string strSqlUpdate = "update SMT_Control_Table set PreviousID=?, NextID=? where ID=?;";


            OpenDB();

            for (int i = 0; i < 1300; i++)
            {
                SmartControlData Folder = list[i];
                OleDbParameter[] parameters = new OleDbParameter[3];

                parameters[0] = new OleDbParameter("PreviousID", OleDbType.VarChar, 50);
                if (Folder.PreviousID == null)
                {
                    Folder.PreviousID = "";
                }
                parameters[0].Value = Folder.PreviousID;

                parameters[1] = new OleDbParameter("NextID", OleDbType.VarChar, 50);
                if (Folder.NextID == null)
                {
                    Folder.NextID = "";
                }
                parameters[1].Value = Folder.NextID;

                parameters[2] = new OleDbParameter("ID", OleDbType.VarChar, 50);
                parameters[2].Value = Folder.ID;
                //OpenDB();
                OleDbCommand cmd = _oleConnection.CreateCommand();

                cmd.CommandText = strSqlUpdate;

                OleDbTransaction transaction = _oleConnection.BeginTransaction();

                cmd.Transaction = transaction;

                cmd.Parameters.Add(parameters[0]);
                cmd.Parameters.Add(parameters[1]);
                cmd.Parameters.Add(parameters[2]);
                cmd.ExecuteNonQuery();
                transaction.Commit();
                //CloseDB();
                //ExecuteNonQuery(strSqlUpdate, parameters);                
            }

正常代码：

public static void SaveControl(List<SmartControlData> list)
        {
            string strSqlUpdate = "update SMT_Control_Table set PreviousID=?, NextID=? where ID=?;";


            OpenDB();

            for (int i = 0; i < 1300; i++)
            {
                SmartControlData Folder = list[i];
                OleDbParameter[] parameters = new OleDbParameter[3];

                parameters[0] = new OleDbParameter("PreviousID", OleDbType.VarChar, 50);
                if (Folder.PreviousID == null)
                {
                    Folder.PreviousID = "";
                }
                parameters[0].Value = Folder.PreviousID;

                parameters[1] = new OleDbParameter("NextID", OleDbType.VarChar, 50);
                if (Folder.NextID == null)
                {
                    Folder.NextID = "";
                }
                parameters[1].Value = Folder.NextID;

                parameters[2] = new OleDbParameter("ID", OleDbType.VarChar, 50);
                parameters[2].Value = Folder.ID;

                ExecuteNonQuery(strSqlUpdate, parameters);               
               
            }

            CloseDB();
        }