asp.net:DropDownListバインディングデータソース及び選択した値の共通方法及び例

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Web.UI.WebControls;
using System.Data;

namespace Common
{
    public abstract class DropDownListHelper
    {
        public readonly string STRING_VALUE = "STRING_VALUE";
        public readonly string STRING_TEXT = "STRING_TEXT";

        public static void SetSource(out string sError,DropDownList ddlCtrl, string sSQL,DataTable dtSource = null, bool bSelectFirstItem = false, string sFirstRowText = "")
        {
            sError = string.Empty;
            DataTable dt = null;

            try
            {
                if (!string.IsNullOrEmpty(sSQL))
                {
                    dt = SqlServerHelper.GetDataTable(out sError,sSQL);
                }
                else if (dtSource != null)
                {
                    dt = dtSource.Copy();
                }
            }
            catch (Exception ex)
            {
                sError = ex.Message.ToString();
                return;
            }

            ddlCtrl.Items.Clear();
            ddlCtrl.DataSource = null;

            if (dt != null && dt.Rows.Count > 0 && dt.Columns.Count > 1) //    2 : id    value  
            {
                if (!string.IsNullOrEmpty(sFirstRowText))
                {
                    DataRow dr = dt.NewRow();
                    dr[dt.Columns[0]] = -1; //      ID    -1
                    dr[dt.Columns[1]] = sFirstRowText;
                    dt.Rows.InsertAt(dr, 0);//     0     
                }

                //ddlCtrl.AutoPostBack = true;
                ddlCtrl.DataSource = dt;
                ddlCtrl.DataValueField = dt.Columns[0].ColumnName; //   ID
                ddlCtrl.DataTextField = dt.Columns[1].ColumnName; //     
                ddlCtrl.DataBind();

                if (bSelectFirstItem) //        
                {
                    int iID = 0;
                    if (Int32.TryParse(dt.Rows[0][0].ToString(), out iID))
                    {
                        ddlCtrl.SelectedValue = iID.ToString();
                    }
                }
                else
                {
                    ddlCtrl.Items.Insert(0, "");//     0     
                }
            }
        }

        public static void SelectItem(out string sError, DropDownList ddlCtrl, string sSQL,string sSelectedValue="")
        {
            sError = string.Empty;

            try
            {
                if (!string.IsNullOrEmpty(sSelectedValue)) ddlCtrl.SelectedValue = sSelectedValue;
                else if (!string.IsNullOrEmpty(sSQL))
                {
                    object oResult = SqlServerHelper.GetSingle(sSQL);
                    if (!Common.Tool.IsNullOrEmptyObject(oResult))
                        ddlCtrl.SelectedValue = oResult.ToString();
                }
            }
            catch (Exception ex)
            {
                sError = ex.Message.ToString();
                return;
            }

 
        }

    }
}

//       :1
            string sError=string.Empty;
            Common.DropDownListHelper.SetSource(out sError, ddlAppName, "",         dataTable,true," ");
            if (!string.IsNullOrEmpty(sError)) { Common.MessageBox.Show(this, sError); return; }
//       :2
            string sError=string.Empty;
            Common.DropDownListHelper.SetSource(out sError, ddlAppName, "        sql  (2    ：id,value)", null,true," ");
            if (!string.IsNullOrEmpty(sError)) { Common.MessageBox.Show(this, sError); return; }
//  dropDownlist     
                    string sSQL = "select GroupID FROM sysUserGroup WHERE AppID= " + hidAppID.Value + " and UserID=" + hidUserID.Value;
                    Common.DropDownListHelper.SelectItem(out sError, ddlGroup, sSQL);
                    if (!string.IsNullOrEmpty(sError)) { Common.MessageBox.Show(this, sError); return; }
//Common.MessageBox.Show   ：
		/// <summary>
		///          
		/// </summary>
		/// <param name="page">      ，   this</param>
		/// <param name="msg">    </param>
		public static void  Show(System.Web.UI.Page page,string msg)
		{
            msg = msg.Replace("'", "\""); //           
            page.ClientScript.RegisterStartupScript(page.GetType(),"message", "<script language='javascript' defer>alert('" + msg.ToString() + "');</script>");
		}
// SqlServerHelper     ：http://blog.csdn.net/keenweiwei/article/details/6845709