方法一：
 1   string sql="SELECT * FROM NewsClass ORDER BY ORDERID DESC";
 2
 3   OleDbConnection conn=new OleDbConnection();
 4
 5   conn.ConnectionString=ConnectionString;
 6   conn.Open();
 7
 8   OleDbCommand cmd = new OleDbCommand(Sql,Conn);
 9   OleDbDataReader dr= cmd.ExecuteReader();
10
11     //将数据添加到 DropDownList
12   while(dr.Read())
13   {
14        ddl.Items.Add(new ListItem(dr["ClassName"].ToString(),dr["ClassId"].ToString()));
15   }
16   dr.Close();
17
18   cmd.Dispose();
19   conn.Close;
20   conn.Dispose();
21
方法二：
 1  string sql="SELECT * FROM NewsClass ORDER BY ORDERID DESC";
 2
 3   OleDbConnection conn=new OleDbConnection();
 4   conn.ConnectionString=ConnectionString;
 5   conn.Open();
 6
 7   DataSet ds=new DataSet();
 8   OleDbDataAdapter da=new OleDbDataAdapter(sql,conn); 
 9   da.Fill(ds,"ClassTable");
10
11   //将数据添加到 DropDownList
12   ddl.DataSource=ds;
13   ddl.DataTextField = "ClassName";
14   ddl.DataValueField = "ClassID";
15   ddl.DataBind();
16
17   ds.Dispose();
18   conn.Close;
19   conn.Dispose();
20
21
http://www.cnblogs.com/meil/archive/2006/10/19/533812.html