using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Configuration;

namespace Example_6_3
{
	/// <summary>
	/// Summary description for MyDropDownList.
	/// </summary>
	public class MyDropDownList : System.Web.UI.Page
	{
		protected System.Web.UI.WebControls.Label SucessMessage;
		protected System.Web.UI.WebControls.ListBox DirectList;
		protected System.Web.UI.WebControls.DropDownList SourceList;
		protected System.Web.UI.WebControls.Button AddBtn;
		protected System.Web.UI.WebControls.Button DeleteBtn;
		private readonly string SQLCONNECTIONSTRING = ConfigurationSettings.AppSettings["SQLCONNECTIONSTRING"].ToString();

		private void Page_Load(object sender, System.EventArgs e)
		{
			if(!Page.IsPostBack)
			{
				///綁定源列表控件的數據
				GetSourceListData();
			}
		}

		#region Web Form Designer generated code
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN: This call is required by the ASP.NET Web Form Designer.
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{    
			this.DeleteBtn.Click += new System.EventHandler(this.DeleteBtn_Click);
			this.AddBtn.Click += new System.EventHandler(this.AddBtn_Click);
			this.Load += new System.EventHandler(this.Page_Load);

		}
		#endregion

		private void GetSourceListData()
		{
			///清空ListBox控件的所有數據項
			SourceList.Items.Clear();

			///創建數據庫的鏈接對象
			String cmdText = "SELECT Staff_ID,Staff_Name from Staff ORDER BY Staff_ID";
			SqlConnection myConnection = new SqlConnection(SQLCONNECTIONSTRING);
			SqlCommand myCommand = new SqlCommand(cmdText,myConnection);

			///查詢數據庫
			myConnection.Open();
			SqlDataReader reader = myCommand.ExecuteReader();				

			///讀取SqlDataReader中的數據
			while(reader.Read())
			{
				SourceList.Items.Add(new ListItem(reader["Staff_Name"].ToString(),reader["Staff_ID"].ToString()));				
			}

			///關閉讀取器和數據庫的鏈接
			reader.Close();
			myConnection.Close();
		}

		private void AddBtn_Click(object sender, System.EventArgs e)
		{
			///添加下拉列表框中選擇的數據項到列表框中
			if(SourceList.SelectedIndex > -1)
			{
				DirectList.Items.Add(SourceList.SelectedItem);
			}

			///清空下拉框和列表框的選項
			SourceList.SelectedIndex = -1;
			DirectList.SelectedIndex = -1;
			SucessMessage.Visible = false;
		}

		private void DeleteBtn_Click(object sender, System.EventArgs e)
		{
			if(DirectList.SelectedIndex > -1)
			{
				///刪除列表框中選擇的數據項
				DirectList.Items.Remove(DirectList.SelectedItem);
				SucessMessage.Visible = false;
			}
			else
			{
				///顯示提示信息
				SucessMessage.Visible = true;
			}
		
		}
	}
}