三级联动练习

Question

webformclassstringnamespaceobject

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;namespace UserWeb
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        
        public string[] gradeList = new string[] { "一年级", "二年级", "三年级" };
        public string[] classList1 = new string[] { "一班", "二班", "三班", "四班" };
        public string[] classList2 = new string[] { "一班", "二班", "三班" };
        public string[] classList3 = new string[] { "一班", "二班" };
        public string[] studentName = new string[] { "1", "2" };
        public string[] studentName1 = new string[] { "2", "3" };
        public string[] studentName2 = new string[] { "4", "5" };
        protected void Page_Load(object sender, EventArgs e)
        {
            ASPxComboBoxGrade.DataSource = gradeList;
            ASPxComboBoxGrade.DataBind();
        }
      
     
        protected void ASPxComboBoxGrade_SelectedIndexChanged(object sender, EventArgs e)
        {
            ASPxComboBoxGrade.Items.Clear();
            ASPxComboBoxGrade.Items.Add(gradeList[0]);
            ASPxComboBoxGrade.Items.Add(gradeList[1]);
            ASPxComboBoxGrade.Items.Add(gradeList[2]);
            string grade = ASPxComboBoxGrade.SelectedItem.ToString();
            if (grade == gradeList[0])
            {
              ASPxComboBoxClass.Items.Clear();
              ASPxComboBoxClass.Items.Add(classList1[0]);
              ASPxComboBoxClass.Items.Add(classList1[1]);
              ASPxComboBoxClass.Items.Add(classList1[2]);
              ASPxComboBoxClass.Items.Add(classList1[3]);
              ASPxComboBoxClass.DataSource = classList1;
              ASPxComboBoxClass.DataBind();
        
          }
            else if( grade == gradeList[1])
            {
                ASPxComboBoxClass.Items.Clear();
                ASPxComboBoxClass.Items.Add(classList2[0]);
                ASPxComboBoxClass.Items.Add(classList2[1]);
                ASPxComboBoxClass.Items.Add(classList2[2]);
                ASPxComboBoxClass.DataSource = classList2;
                ASPxComboBoxClass.DataBind();
            
            }
            else if (grade == gradeList[2])
            {
                ASPxComboBoxClass.Items.Clear();
                ASPxComboBoxClass.Items.Add(classList3[0]);
                ASPxComboBoxClass.Items.Add(classList3[1]);
                ASPxComboBoxClass.DataSource = classList3;
                ASPxComboBoxClass.DataBind();
            }        }        protected void ASPxComboBoxClass_SelectedIndexChanged(object sender, EventArgs e)
        {
            string class1 = ASPxComboBoxClass.SelectedItem.ToString();
            if (class1 == gradeList[0])
            {
                ASPxComboBoxStudentName.Items.Clear();
                ASPxComboBoxStudentName.Items.Add(studentName[0]);
                ASPxComboBoxStudentName.Items.Add(studentName[1]);
            }
            else if (class1 == gradeList[1])
            {
                ASPxComboBoxStudentName.Items.Clear();
                ASPxComboBoxStudentName.Items.Add(studentName1[0]);
                ASPxComboBoxStudentName.Items.Add(studentName[1]);            }
            else if (class1 == gradeList[2])
            {
                ASPxComboBoxStudentName.Items.Clear();
                ASPxComboBoxStudentName.Items.Add(studentName[0]);
                ASPxComboBoxStudentName.Items.Add(studentName[1]);            }
        }        protected void ASPxComboBoxStudentName_SelectedIndexChanged(object sender, EventArgs e)
        {        }
    }
}刚才发的不对，这个事，求帮帮忙改一改呀

Answer 2

http://blog.csdn.net/xianfajushi/article/details/5928136

Answer 3

            ASPxComboBoxGrade.Items.Clear();
            ASPxComboBoxGrade.Items.Add(gradeList[0]);
            ASPxComboBoxGrade.Items.Add(gradeList[1]);
            ASPxComboBoxGrade.Items.Add(gradeList[2]);
这里为什么要清空他又加回来？没什么意义啊。  string grade = ASPxComboBoxGrade.SelectedItem.Value.ToString();  试试 以下的SelectedItem也这样改看看。

Answer 4

调用数据库信息三级联动示例
//下拉框控件设置
  <asp:UpdatePanel runat="server">
                      <ContentTemplate>
                            <asp:DropDownList ID="ddlProvince" runat="server" AutoPostBack="True" 
                                onselectedindexchanged="ddlProvince_SelectedIndexChanged">
                            </asp:DropDownList>
                                   <asp:DropDownList ID="ddlCity" runat="server" AutoPostBack="true" 
                                onselectedindexchanged="ddlCity_SelectedIndexChanged">
                            </asp:DropDownList>
                            <asp:DropDownList ID="ddlArea" runat="server">
                            </asp:DropDownList>
                        </ContentTemplate>
                    </asp:UpdatePanel>
//加载数据库信息显示
SqlConnection sqlcon;
    string strCon = ConfigurationManager.AppSettings["conn"];
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            sqlcon = new SqlConnection(strCon);
            string sqlstr = "select Province from tb_Province";
            sqlcon.Open();
            SqlDataAdapter myda = new SqlDataAdapter(sqlstr, sqlcon);
            DataSet myds = new DataSet();  
            myda.Fill(myds);
            ddlProvince.DataSource= myds;
            ddlProvince.DataValueField = "Province";
            ddlProvince.DataBind();            string strCity = "select * from tb_City where Province='" + ddlProvince.SelectedItem.Text + "'";
            SqlDataAdapter mydaCity = new SqlDataAdapter(strCity, sqlcon);
            DataSet mydsCity = new DataSet();
            mydaCity.Fill(mydsCity);
            ddlCity.DataSource = mydsCity;
            ddlCity.DataValueField = "City";
            ddlCity.DataBind();            string strArea = "select * from tb_Area where City='" + ddlCity.SelectedItem.Text + "'";
            SqlDataAdapter mydaArea = new SqlDataAdapter(strArea, sqlcon);
            DataSet mydsArea = new DataSet();
            mydaArea.Fill(mydsArea);
            ddlArea.DataSource = mydsArea;
            ddlArea.DataValueField = "Area";
            ddlArea.DataBind();
            sqlcon.Close();
        }//codego.net/tags/11/1/
//点选按钮显示下级菜单
 protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e)
    {
        sqlcon = new SqlConnection(strCon);
        string sqlstr = "select * from tb_City where Province='" + ddlProvince.SelectedItem.Text + "'";
        SqlDataAdapter myda = new SqlDataAdapter(sqlstr, sqlcon);
        DataSet myds = new DataSet();
        sqlcon.Open();
        myda.Fill(myds);
        ddlCity.DataSource = myds;
        ddlCity.DataValueField = "City";
        ddlCity.DataBind();
        sqlcon.Close();
    }
    protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)
    {
        sqlcon = new SqlConnection(strCon);
        string sqlstr2 = "select * from tb_Area where City='" + ddlCity.SelectedItem.Text + "'";
        SqlDataAdapter mysda = new SqlDataAdapter(sqlstr2, sqlcon);
        DataSet myds2 = new DataSet();
        sqlcon.Open();
        mysda.Fill(myds2);
        ddlArea.DataSource = myds2;
        ddlArea.DataValueField = "Area";
        ddlArea.DataBind();
        sqlcon.Close();
    }