combobox数据绑定

Code
        public void fill_combobox_reader(string sql,ComboBox combo,string tablename,string read_value)
        {                
            co.co();
            SqlDataAdapter adapter = new SqlDataAdapter(sql, co.conn);
            DataSet ds = new DataSet();
            adapter.Fill(ds,tablename);
            combo.DataSource = ds.Tables[tablename];
            combo.DisplayMember = read_value;
            combo.ValueMember = read_value;
            co.dis_co();
        }