Binding Dropdownlist with dataset values in ASP.NET

private void FillDropDownList()
{
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString);

SqlCommand cmd = new SqlCommand("Select * from students", con);

SqlDataAdapter da = new SqlDataAdapter(cmd);

DataSet ds = new DataSet();
da.Fill(ds);

DropDownList1.DataTextField = ds.Tables[0].Columns["FullName"].ToString();
DropDownList1.DataValueField = ds.Tables[0].Columns["id"].ToString();

DropDownList1.DataSource = ds.Tables[0];
DropDownList1.DataBind();
}