private void buttonDisconnect_Click(object sender, EventArgs e)
        {
            if (_DB2Access == null)
            {
                return;
            }

            try
            {
                _DB2Access.Close();
                _DB2Access = null;

                FieldsLock(true);
                FieldsImageLock(true);
                FieldsClear(false);
            }
            catch (System.Exception ex)
            {
                this.labelMsg.Text = ex.Message;
            }
        }