DropdownList綁定的兩種方法
動態綁定方法一：動態綁定數據庫中的字段。

SqlConnection conn = UtilitySqlClass.OperateDataBase.ReturnConn();
string strSQL = "select * from CompanyType";
SqlDataAdapter ada = new SqlDataAdapter(strSQL, conn);
DataSet ds = new DataSet();
ada.Fill(ds, "CompanyType");
DropDownList1.DataSource = ds.Tables["CompanyType"].DefaultView;
DropDownList1.DataValueField = ds.Tables["CompanyType"].Columns[1].ColumnName;
DropDownList1.DataTextField = ds.Tables["CompanyType"].Columns[1].ColumnName;
DropDownList1.DataBind();
ds.Dispose();

動態綁定方法二：利用DropDownList.Items.Add方法。

PRotected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
SqlConnection conn = UtilitySqlClass.OperateDataBase.ReturnConn();
try
{
conn.Open();
this.DropDownList1.Items.Add("");
string strSQL = "select CompanyType from CompanyType";
SqlCommand com = new SqlCommand(strSQL, conn);
SqlDataReader dr = com.ExecuteReader();
while (dr.Read())
{
this.DropDownList1.Items.Add(dr["CompanyType"].ToString());
}
}
catch (Exception ex)
{
Response.Write("<scirpt>alert('" + ex.Message.ToString() + "')</scr}
finally
{
conn.Close();
}
}
}

第一種方法：
        string ConnString = ConfigurationSettings.AppSettings["ConnectionString"];
         //創建一個SqlConnection
         SqlConnection Conn = new SqlConnection( ConnString );      

         string SQL_Select = "select id, ItemName from DDLItem order by id desc";

         //構造一個SqlDataAdapter

         SqlDataAdapter myAdapter = new SqlDataAdapter( SQL_Select, Conn);

         //開始讀取數據

         Conn.Open();

         DataSet dataSet = new DataSet();

         myAdapter.Fill( dataSet,"Table1" );

         Conn.Close();

         //開始綁定DropDownList

         //指定DropDownList使用的數據源

         DropDownList1.DataSource = dataSet.Tables["Table1"].DefaultView;

         //指定DropDownList使用的表里的那些字段

         DropDownList1.DataTextField = "ItemName"; //dropdownlist的Text的字段

         DropDownList1.DataValueField = "id";//dropdownlist的Value的字段

         DropDownList1.DataBind();

第二種方法：
        con.Open();
        SqlCommand cmd = new SqlCommand(strSql,con);
        SqlDataReader dr = cmd.ExecuteReader();
        while (dr.Read())
        {     
            DropDownList1.Items.Add(new ListItem(dr["status"].ToString(), dr["status_Id"].ToString()));
        }