protected void Button1_Click(object sender, EventArgs e)
{
BoundField boundField = new BoundField();
boundField.DataField = "DOB";
boundField.HeaderText = "DOB";
boundField.HtmlEncode = false;
boundField.DataFormatString = "{0:d}";
GridView1.Columns.Add(boundField);
//bind gridview..

bindgridview();
}