帮我看下 怎么dropDownlist不显示数据

string bianhao = TextBox1.Text;
string mingcheng = TextBox2.Text;
string jieshao = Request.Form["content1"];
string renyuan = TextBox3.Text;
string shebei = TextBox4.Text;
string lianxi = TextBox5.Text;
string yiyuanbianhao = TextBox6.Text;
SqlConnection conn = new SqlConnection("server=localhost;database=h204223;uid=sa;pwd=sa ");
conn.Open();
string strsql1 = "select * from class where class ='health_class'";
SqlDataAdapter apt = new SqlDataAdapter(strsql1, conn);
DataSet ds = new DataSet();
apt.Fill(ds,"asd1");
DropDownList1.DataSource = ds.Tables["asd1"].DefaultView;
DropDownList1.DataTextField = "name";
DropDownList1.DataValueField = "id";