C# access日期查询加#

C# access日期查询加#
if (((string)((ComboBoxItem)cmbField.SelectedItem).Value).Equals("System.DateTime"))
{
                    //判断日期的;
                
                    if (checkBox1.Checked == true)
                    {
                        value = "#" + cmbValue.SelectedItem.ToString().Trim() + "#";
                    }
}