datagrid更新数据。取得textbox中的数据

private void DataGrid1_UpdateCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
string id=DataGrid1.DataKeys[e.Item.ItemIndex].ToString();
string name=((TextBox)e.Item.Cells[1].Controls[0]).Text;
string address=((TextBox)e.Item.Cells[2].Controls[0]).Text;
string sql="update customers "+" set companyname='"+name+"',"+"address='"+address+"'"+" where customerid='"+id+"'";
DataSet ds1=new DataSet();

SqlDataAdapter da=new SqlDataAdapter(sql,this.con);
SqlCommand comm=new SqlCommand(sql,this.con);
comm.CommandType=CommandType.Text;
con.Open();
comm.ExecuteNonQuery();
DataGrid1.EditItemIndex=-1;
con.Close();
show();

}