更新SQL数据库有关问题

更新SQL数据库问题
private void button3_Click(object sender, EventArgs e)
  {int i=0;
  string strConn = ConfigurationManager.ConnectionStrings["字符串"].ConnectionString;
  SqlConnection myConn = new SqlConnection(strConn);
  string upSQL = " select lat,lng from shuju ";

  myConn.Open();
  SqlCommand myCommand1 = new SqlCommand(upSQL, myConn);
  SqlDataAdapter adapter1 = new SqlDataAdapter(myCommand1);
  adapter1.SelectCommand = new SqlCommand(upSQL,myConn);
  SqlCommandBuilder builder = new SqlCommandBuilder(adapter1);
  DataSet ds1 = new DataSet();
  adapter1.Fill(ds1);
  DataTable dt1 = ds1.Tables[0];
  for(i=0;i<dt1.Rows.Count;i++){
  dt1.Rows[i][0] = 22.22;
  }

  adapter1.Update(dt1);
  myConn.Close();

  }
数据库的表里是有主键的 字段名为id

为什么更新不了呢

------解决方案--------------------
select lat,lng,id from shuju