关于dropdownlist下拉框的三级联动和后台代码整合

Question

我是一个刚接触开发没多久的新人。。= =最近用dropdownlist控件设置三级联动的时候，第一个和第二个联动的很正常，可是第二个和第三个联动的时候，第三个dropdownlist控件不管怎么样都一直为空，（正常是有数据的）下面是我的代码，谁能帮我去看下是哪边问题哦。
还有就是我觉得我现在后台这个联动的代码写的重复性太多，但是我不知道怎么整合好，能给我写个整合后的例子吗?string strCon = ConfigurationManager.AppSettings["MsSql"];
        protected void Page_Load(object sender, EventArgs e)
        {
         if (!IsPostBack)
            {
                BindUserList();                ddlGroupIDBind();
                ddlU_CNameBind();
                ddlUserIDBind();
                ddlDutyBind();            }
        }
        //部门下拉框
        protected void ddlGroupIDBind()
        {
            string sqlSel = "select  GroupID,G_CName from sys_Group where G_ParentID !=0  order by GroupID ";
            SqlConnection con = new SqlConnection(strCon); ;
            con.Open();
            SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            ddlGroupID.DataSource = ds.Tables[0].DefaultView;
            ddlGroupID.DataTextField = "G_CName";
            ddlGroupID.DataValueField = "GroupID";
            ddlGroupID.DataBind();
        }        //员工姓名下拉框
        protected void ddlU_CNameBind()
        {
            string sqlSel = "select UserID,U_CName from sys_User where U_GroupID='" + ddlGroupID.SelectedValue + "' order by UserID  ";
            SqlConnection con = new SqlConnection(strCon);
            con.Open();
            SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            ddlUCName.DataSource = ds.Tables[0].DefaultView;
            ddlUCName.DataTextField = "U_CName";
            ddlUCName.DataValueField = "UserID";
            ddlUCName.DataBind();
        }        //员工编号
        protected void ddlUserIDBind()
        {
            string sqlSel = "select UserID from sys_User where U_CName='" + ddlUCName.SelectedValue + "' order by UserID  ";
            SqlConnection con = new SqlConnection(strCon);
            con.Open();
            SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            ddlUserID.DataSource = ds.Tables[0].DefaultView;
            ddlUserID.DataTextField = "UserID";
            ddlUserID.DataValueField = "UserID";
            ddlUserID.DataBind();
        }        //部门下拉框和姓名下拉框的二级联动触发事件
        protected void ddlGroupID_SelectedIndexChanged(object sender, EventArgs e)
        {
            string U_GroupID = this.ddlGroupID.SelectedValue;
            SqlConnection con = new SqlConnection(strCon);
            con.Open();
            SqlCommand cmd = new SqlCommand("select UserID,U_CName from sys_User where U_GroupID='" + ddlGroupID.SelectedValue + "' order by UserID ", con);
            SqlDataReader sdr = cmd.ExecuteReader();
            this.ddlUCName.DataSource = sdr;
            this.ddlUCName.DataTextField = "U_CName";
            this.ddlUCName.DataValueField = "UserID";
            this.ddlUCName.DataBind();
            sdr.Close();
            con.Close();        }        //姓名下拉框和员工编号下拉框的二级联动触发事件
        protected void ddlUCName_SelectedIndexChanged(object sender, EventArgs e)
        {
            string UserID = this.ddlUCName.SelectedValue;
            SqlConnection con = new SqlConnection(strCon);
            con.Open();
            SqlCommand cmd = new SqlCommand("select UserID from sys_User where U_CName='" + ddlUCName.SelectedValue + "' order by UserID ", con);
            SqlDataReader sdr = cmd.ExecuteReader();
            this.ddlUserID.DataSource = sdr;
            this.ddlUserID.DataTextField = "UserID";
            this.ddlUserID.DataValueField = "UserID";
            this.ddlUserID.DataBind();
            sdr.Close();
            con.Close();        }        //权限下拉框
        protected void ddlDutyBind()
        {
            string sqlSel = "select  ID,Duty from sys_Permission  order by ID  ";
            SqlConnection con = new SqlConnection(strCon);
            con.Open();
            SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            ddlDuty.DataSource = ds.Tables[0].DefaultView;
            ddlDuty.DataTextField = "Duty";
            ddlDuty.DataValueField = "Duty";
            ddlDuty.DataBind();
        }
        //权限等级下拉框
        protected void ddlLvBind()
        {
            string sqlSel = "select  ID,Lv from sys_Permission where Duty='" + ddlDuty.SelectedValue + "'  order by ID  ";
            SqlConnection con = new SqlConnection(strCon);
            con.Open();
            SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            ddlLv.DataSource = ds.Tables[0].DefaultView;
            ddlLv.DataTextField = "Lv";
            ddlLv.DataValueField = "Lv";
            ddlLv.DataBind();
        }
        //权限和权限等级二级联动触发事件
        protected void ddlDuty_SelectedIndexChanged(object sender, EventArgs e)
         {
             string Duty = this.ddlDuty.SelectedValue;
            SqlConnection con = new SqlConnection(strCon);
            con.Open();
            SqlCommand cmd = new SqlCommand("select  ID,Lv from sys_Permission where Duty='" + ddlDuty.SelectedValue + "'  order by ID ", con);
            SqlDataReader sdr = cmd.ExecuteReader();
            this.ddlLv.DataSource = sdr;
            this.ddlLv.DataTextField = "Lv";
            this.ddlLv.DataValueField = "Lv";
            this.ddlLv.DataBind();
            sdr.Close();
            con.Close();        }

Answer 1

Refer sample:
http://www.cnblogs.com/insus/archive/2012/10/16/2725307.html
http://www.cnblogs.com/insus/archive/2011/07/04/2097059.html

Answer 2

你的dropdowmlist有没有加 AutoPostBack="True" 这个属性？

Answer 3

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindUserList();
ddlGroupIDBind();
ddlU_CNameBind();
ddlUserIDBind();
ddlDutyBind();
} }
string strCon = ConfigurationManager.AppSettings["MsSql"]; //部门下拉框
protected void ddlGroupIDBind()
{
string sqlSel = "select  GroupID,G_CName from sys_Group where G_ParentID !=0  order by GroupID ";
SqlConnection con = new SqlConnection(strCon); ;
con.Open();
SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
DataSet ds = new DataSet();
sda.Fill(ds);
ddlGroupID.DataSource = ds.Tables[0].DefaultView;
ddlGroupID.DataTextField = "G_CName";
ddlGroupID.DataValueField = "GroupID";
ddlGroupID.DataBind();
} //员工姓名下拉框
protected void ddlU_CNameBind()
{
string sqlSel = "select UserID,U_CName from sys_User where U_GroupID='" + ddlGroupID.SelectedValue + "' order by UserID  ";
SqlConnection con = new SqlConnection(strCon);
con.Open();
SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
DataSet ds = new DataSet();
sda.Fill(ds);
ddlUCName.DataSource = ds.Tables[0].DefaultView;
ddlUCName.DataTextField = "U_CName";
ddlUCName.DataValueField = "UserID";
ddlUCName.DataBind();
} //员工编号
protected void ddlUserIDBind()
{
string sqlSel = "select UserID from sys_User where U_CName='" + ddlUCName.SelectedValue + "' order by UserID  ";
SqlConnection con = new SqlConnection(strCon);
con.Open();
SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
DataSet ds = new DataSet();
sda.Fill(ds);
ddlUserID.DataSource = ds.Tables[0].DefaultView;
ddlUserID.DataTextField = "UserID";
ddlUserID.DataValueField = "UserID";
ddlUserID.DataBind();
} //部门下拉框和姓名下拉框的二级联动触发事件
protected void ddlGroupID_SelectedIndexChanged(object sender, EventArgs e)
{
ddlU_CNameBind(); } //姓名下拉框和员工编号下拉框的二级联动触发事件
protected void ddlUCName_SelectedIndexChanged(object sender, EventArgs e)
{
ddlUserIDBind();
} //权限下拉框
protected void ddlDutyBind()
{
string sqlSel = "select  ID,Duty from sys_Permission  order by ID  ";
SqlConnection con = new SqlConnection(strCon);
con.Open();
SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
DataSet ds = new DataSet();
sda.Fill(ds);
ddlDuty.DataSource = ds.Tables[0].DefaultView;
ddlDuty.DataTextField = "Duty";
ddlDuty.DataValueField = "Duty";
ddlDuty.DataBind();
}
//权限等级下拉框
protected void ddlLvBind()
{
string sqlSel = "select  ID,Lv from sys_Permission where Duty='" + ddlDuty.SelectedValue + "'  order by ID  ";
SqlConnection con = new SqlConnection(strCon);
con.Open();
SqlDataAdapter sda = new SqlDataAdapter(sqlSel, con);
DataSet ds = new DataSet();
sda.Fill(ds);
ddlLv.DataSource = ds.Tables[0].DefaultView;
ddlLv.DataTextField = "Lv";
ddlLv.DataValueField = "Lv";
ddlLv.DataBind();
}
//权限和权限等级二级联动触发事件
protected void ddlDuty_SelectedIndexChanged(object sender, EventArgs e)
{
ddlLvBind();
} 
给你精简了下。然后你在看看能关联出数据不。不行的话再看看。
注意：第三个的_SelectedIndexChanged 事件，AutoPostBack="True" 

Answer 4

<table border="0" cellspacing="1" cellpadding="0" class="Permission" > 
           <tr>
           <td style="width:100px;height:30px" align="center">
            所属部门
           </td>
           <td style="width:200px;height:30px" align="center">
           <asp:DropDownList ID="ddlGroupID" runat="server" Width="100px"  onselectedindexchanged="ddlGroupID_SelectedIndexChanged" AutoPostBack="true"></asp:DropDownList>
           </td>
           </tr>           <tr>
           <td style="width:100px;height:30px" align="center" >
            员工姓名
           </td>
           <td style="width:200px;height:30px" align="center">
           <asp:DropDownList ID="ddlUCName" runat="server" Width="100px" onselectedindexchanged="ddlUCName_SelectedIndexChanged" AutoPostBack="true"></asp:DropDownList>
           </td>
           </tr>           <tr>
           <td style="width:100px;height:30px" align="center">
            员工编号
           </td>
           <td style="width:200px;height:30px" align="center">
           <asp:DropDownList ID="ddlUserID" runat="server" Width="100px"  AutoPostBack="true"></asp:DropDownList>
           </td>
           </tr>           <tr>
           <td style="width:100px;height:30px" align="center">
            权限名称
           </td>
           <td style="width:200px;height:30px" align="center">
           <asp:DropDownList ID="ddlDuty" runat="server" Width="100px" onselectedindexchanged="ddlDuty_SelectedIndexChanged" AutoPostBack="true"></asp:DropDownList>
           </td>
           </tr>           <tr>
           <td style="width:100px;height:30px" align="center">
            权限等级
           </td>
           <td style="width:200px;height:30px" align="center">
           <asp:DropDownList ID="ddlLv" runat="server" Width="100px"></asp:DropDownList>
           </td>
           </tr>
</table>这个是我前台哦

Answer 5

3楼那样改没问题哦，就是我第三个dropdownlist还是关联不起来，是哪边问题哦