實現二級聯動菜單 C#，帶完整資料庫 SQL

----------------db.cs------------------------------

   // TODO: 在此處添加建構函式邏輯
   //
  }
  public static SqlConnection createConnection()
 {
 SqlConnection con=new SqlConnection("server=.;database=list;uid=sa;pwd=;");
   return con;
 }
 }
}


--------------------------.cs源檔案--------------------------------

private void Page_Load(object sender, System.EventArgs e)
  {
   if(!Page.IsPostBack)
   {
    SqlConnection con=db.createConnection();
    con.Open();
    SqlCommand cmd=new SqlCommand("select * from sheng",con);
    SqlDataReader sdr=cmd.ExecuteReader();
    this.sheng.DataSource=sdr;
    this.sheng.DataTextField="sheng";
    this.sheng.DataValueField="shengid";
    this.sheng.DataBind();
    sdr.Close();
    cmd.CommandText="select * from city where shengid=1";
    sdr=cmd.ExecuteReader();
    this.city.DataSource=sdr;
    this.city.DataTextField="cityname";
    this.city.DataValueField="cityid";
    this.city.DataBind();
    sdr.Close();
    con.Close();
   }
  }
  #region Web Form設計器產生的程式碼
  override protected void OnInit(EventArgs e)
  {
   //
   // CODEGEN: 該調用是 ASP.NET Web Form設計器所必需的。
   //
   InitializeComponent();
   base.OnInit(e);
  }
  
  /// <summary>
  /// 設計器支援所需的方法 - 不要使用代碼編輯器修改
  /// 此方法的內容。
  /// </summary>
  private void InitializeComponent()
  {   
   this.sheng.SelectedIndexChanged += new System.EventHandler(this.DropDownList1_SelectedIndexChanged);
   this.Button1.Click += new System.EventHandler(this.Button1_Click);
   this.Calendar1.SelectionChanged += new System.EventHandler(this.Calendar1_SelectionChanged);
   this.rdl.SelectedIndexChanged += new System.EventHandler(this.drl_SelectedIndexChanged);
   this.mar.SelectedIndexChanged += new System.EventHandler(this.mar_SelectedIndexChanged);
   this.Load += new System.EventHandler(this.Page_Load);

  }
  #endregion

  private void Button1_Click(object sender, System.EventArgs e)
  {
   
  }
  private void DropDownList1_SelectedIndexChanged(object sender, System.EventArgs e)
  {
   SqlConnection con=db.createConnection();
   con.Open();
   SqlCommand cmd=new SqlCommand("select * from city where shengid="+this.sheng.SelectedValue.ToString(),con);
   SqlDataReader sdr=cmd.ExecuteReader();
   this.city.DataSource=sdr;
   this.city.DataTextField="cityname";
   this.city.DataValueField="cityid";
   this.city.DataBind();
   sdr.Close();
   con.Close();
  }

-----------------------sql檔案-----------------------

create database list

use list

create table sheng
(
 shengid int primary key,
 sheng varchar(50) not null,
)

insert into sheng values(1,'四川')
insert into sheng values(2,'安徽')
insert into sheng values(3,'河南')
insert into sheng values(4,'重慶')
insert into sheng values(5,'廣西')

select * from sheng

create table city
(
 cityid int primary key,
 shengid int foreign key references sheng(shengid),
 cityname varchar(50) not null,
)

insert into city values(1,1,'成都')
insert into city values(2,1,'綿陽')
insert into city values(3,1,'廣元')
insert into city values(4,2,'合肥')
insert into city values(5,2,'蚌埠')
insert into city values(6,2,'淮南')
insert into city values(7,3,'鄭州')
insert into city values(8,3,'開封')
insert into city values(10,3,'商丘')
insert into city values(11,4,'墊江')
insert into city values(12,4,'江津')
insert into city values(13,4,'重慶')
insert into city values(14,5,'南寧')
insert into city values(15,5,'柳州')
insert into city values(16,5,'白色')

select * from city

---------如果有朋友學習要用的話最好看清楚，呵呵，我是邊做邊寫的，並不是可以一次執行成功的------