ASP.NET实现省市县三级联动

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

GetProvince();

}

}

private void LoadData(string id, DropDownList ddl)

{

string strcon = @"Data Source=;Initial Catalog=;Persist Security Info=True;User ID=sa;Password=";

SqlConnection conn = new SqlConnection(strcon);

SqlCommand cmd = conn.CreateCommand();

cmd.CommandText = "SELECT A_Id,A_Name FROM T_Arear WHERE
A_ParentId=@parentid ORDER BY A_Id";

cmd.Parameters.AddWithValue("@parentid", id);

SqlDataAdapter adapter = new SqlDataAdapter(cmd);

DataTable dt = new DataTable();

adapter.Fill(dt);

cmd.Dispose();

conn.Dispose();

ddl.DataSource = dt;

//指定下拉列表要显示的字段的值

ddl.DataTextField = "A_Name";

//指定下拉列表的value属性要绑定的字段的值

ddl.DataValueField = "A_Id";

ddl.DataBind();

//插入默认选中项

if (id == "0")

{

ListItem item = new ListItem("---请选择---", "0");

//this.ddlProvince.Items.Add(item);

ddl.Items.Insert(0, item);

}

}

private void GetProvince()

{

LoadData("0", this.ddlProvince);

}

private int Sum(int x, int y)

{

int num = x + y;

return num;

}

protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e)

{

string id = this.ddlProvince.SelectedItem.Value;

if (id != "0")

{

LoadData(id, this.ddlCity);

string selectid = this.ddlCity.SelectedItem.Value;

LoadData(selectid, this.ddlArear);

}

else

{

ddlCity.Items.Clear();

ddlArear.Items.Clear();

}

}

protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)

{

string id = this.ddlCity.SelectedItem.Value;

LoadData(id, this.ddlArear);

}

}