Binding bind = new Binding("Text", bindsourse, name, true, DataSourceUpdateMode.OnValidation, DBNull.Value);
                            tb.DataBindings.Add(bind);
                            bind.DataSourceNullValue = DBNull.Value;
                            if (((System.Data.DataView)bindsourse.DataSource).Table.Columns[name].DataType.FullName == "System.Decimal")
                            {
                                //下面两句用于处理数值型字段绑定无法设置空值问题
                                bind.Format += new ConvertEventHandler(bind_Format);
                                bind.Parse += new ConvertEventHandler(bind_Parse);
                            }void bind_Format(object sender, ConvertEventArgs e)//绑定控件时发生
        {
            if (e.Value == DBNull.Value)
                e.Value = "";
        }void bind_Parse(object sender, ConvertEventArgs e)//控件值更改时发生
        {
            if (e.Value.ToString() == "")
                e.Value = DBNull.Value;
        }