使用数据读取器填充列表框，并在最后项加入一个，并使之成为默认项

在Page_Load事件中加入以下代码：

if (!IsPostBack)

            {

                SqlDataReader r;

                cnFriends.Open();

     

                // Initialize comboboxes

                try

                {

                    r = cmPlace.ExecuteReader();

                    cbPlace.DataSource = r;

                    cbPlace.DataBind();

                    r.Close();

                    cbPlace.Items.Add(new ListItem("-- Not selected --", "0"));

                    cbPlace.SelectedIndex = cbPlace.Items.Count - 1;

 

                    r = cmType.ExecuteReader();

                    cbType.DataSource = r;

                    cbType.DataBind();

                    r.Close();

                    cbType.Items.Add(new ListItem("-- Not selected --", "0"));

                    cbType.SelectedIndex = cbType.Items.Count - 1;

                }

                finally

                {

                    cnFriends.Close();  // Ensure connection is closed

                }

            }

在取cbType的值时一定要先判断它的值是否为0

如：    if (cbPlace.SelectedItem.Value != "0")

            {

                qry.Append("PlaceID = '");

                qry.Append(cbPlace.SelectedItem.Value).Append("' AND ");

            }