asp.net数据库操作4——scalar

if(!Page.IsPostBack)
   {
    SqlConnection conn = new SqlConnection(con);
    conn.Open();

    string strSql = "select count(id) as countID from 公告";
    SqlCommand cm = new SqlCommand(strSql,conn);

    string intCount = cm.ExecuteScalar().ToString();
    conn.Close();

    Label1.Text = intCount;
   }