private void GetSourceListData()
            string cmdText = "SECECT powerid,powername from power";
            DataTable table =ReturnSqlex(cmdText);
            
                SoureList.DataSource = table.DefaultView;
                SoureList.DataTextField = "powername";
                SoureList.DataValueField = "powerid";
                SoureList.DataBind();
                SoureList.Items.Insert(0, new ListItem("请选择", ""));
                SoureList.DataBind();

        }

        public DataTable ReturnSqlex(string strSql)//调用此方法返回一个datatable
        {

            SqlConnection con = new SqlConnection(
                ConfigurationSettings.AppSettings["SQLCONNECTIONSTRING"]);

            try
            {
                con.Open();
                SqlCommand cmd = new SqlCommand(strSql, con);
                SqlDataAdapter sdr = new SqlDataAdapter();
                sdr.SelectCommand = cmd;
                DataSet ds = new DataSet();
                sdr.Fill(ds, "table");
                return ds.Tables["table"];
            }
            catch (SqlException ex)
            {
                //抛出异常
                throw new Exception(ex.Message, ex);
            }
            finally
            {   ///关闭链接
                con.Close();
            }
        }

将代码改成这样的：
SoureList.DataSource = table.DefaultView;
                SoureList.DataTextField = "powername";
                SoureList.DataValueField = "powerid";
                SoureList.DataBind();
                SoureList.Items.Insert(0, new ListItem("请选择", ""));
             //   SoureList.DataBind();
插入是不需要再绑定的……

已经去掉了，运行没错误，但就是没有显示数据，而数据库中确实有数据，怎么回事啊，已经好几天了，一直没有解决啊，

绑定代码应该是没有问题的，你先把绑定的代码注释掉，然后：
DataRow[] rs=table.rows;
foreach(DataRow row in rs)
{
response.write(row["powername"]);
response.write(row["powerid"]);
}
要是没有数据则就是没有读出数据，要是有那就是绑定的问题……
要不光会写程序还要学会调试程序……

我已经把rows改成了Rows，response.write改成了Response.Write　但是又出现了错误，"proid"字段是int 型的
无法将类型“System.Data.DataRowCollection”隐式转换为“System.Data.DataRow[]”