根据下拉列表选择填写另一个下拉列表 [英] Based on Drop down list selection fill another dropdownlist

问题描述

如何根据第一个选项填写第二个下拉列表。

i想要使用条件：

例如：

How to fill a second dropdownlist based on the selection made in the first one.
i want to use a condition:
for example:

protected void dropdownlist1_SelectedIndexChanged(object sender, EventArgs e)
       {

           if (dropdownlis1t.SelectedValue == "1")
           {
               SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings[""].ConnectionString);
               con.Open();

               SqlCommand cmd = new SqlCommand("Select [Code] from Table where Index= ''3'' OR Index= ''2''", con);
               SqlDataAdapter da = new SqlDataAdapter(cmd);
               DataSet ds = new DataSet();
               da.Fill(ds);
               con.Close();
               dropdownlist2.DataSource = ds;
               dropdownlist2.DataTextField = "Code";
               dropdownlist2.DataValueField = "Code";
               dropdownlist2.DataBind();

           }
           else
               if (dropdownlist1.SelectedValue == "2")
               {

                   SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings[""].ConnectionString);
                   con.Open();

                     SqlCommand cmd = new SqlCommand("Select [Code] from Table where Index= ''1''", con);
               SqlDataAdapter da = new SqlDataAdapter(cmd);
               DataSet ds = new DataSet();
               da.Fill(ds);
               con.Close();
               dropdownlist2.DataSource = ds;
               dropdownlist2.DataTextField = "Code";
               dropdownlist2.DataValueField = "Code";
               dropdownlist2.DataBind();
               }

推荐答案

根据您的代码......值不会填充到下拉列表中。

according to your code..the values does not populate to the dropdownlist.

dropdownlist2.DataTextField = "Code";
                dropdownlist2.DataValueField = "Code";

因为，它不会保留值，但它只是将值分配给

下拉列表文本字段和值字段。



来填充。这是方法之一



准备数据集;

数据集dv;

because, it will not hold the values but it just assigns the values to the
dropdownlist textfield and value field.

to populate.this is one of the method

prepare the dataset;
dataset dv;

int n = dv.Tables["tblcountry"].Rows.Count;

     DropDownList.Items.Clear();
     DropDownList.Items.Add("--Select--");

     for (int i = 0; i <= n - 1; i++)
     {
         DropDownList.DataSource = dv;
         ListItem li = new ListItem();
         li.Text = dv.Tables["tblcountry"].Rows[i][1].ToString();
         li.Value = dv.Tables["tblcountry"].Rows[i][0].ToString();
         DropDownList.Items.Add(li);
     }

它可以尝试这种方法。

it works try this method.

我认为你需要每当执行一次回调，第一次下拉变化。我写这段代码已经很久了。此链接可能会有所帮助。

http://support.microsoft.com/kb/910450 [ ^ ]

I think you need to perform a callback whenever, the first drop down changes. It''s being a long time I wrote code to do that. This link could be helpful.
http://support.microsoft.com/kb/910450[^]

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