下拉列表问题 [英] drop down list concerns

问题描述

我有两个下拉列表作为DDL1和DDL2。我在DDL1中有3个项目，其中第1项是--SELECT--。当我在DDL1中选择第22个项目时，DDL2的项目将从数据库中填充。但问题是，当我在DDL1中选择--SELECT--项目时，先前在DDL2中选择的项目保持原样并且不会删除。我希望当我在DDL1中选择--SELECT--时， DDL2应该为空，当我从DDL1中选择第一个或第二个项目时，应该从数据库中填充DDL2。有人可以帮忙吗？

解决方案

请试试这个...





link1

您需要在SelectedIndexChanged事件上执行此操作。

  protected   void  ddlSparte_SelectedIndexChanged（ object  sender，EventArgs e）
 {
 DataRow dr = dt.NewRow（ ）; 
 dr [  Produktname] =    ... SELECT ...; 
 dr [  Produkt_id] =    0; 
 dt.Rows.InsertAt（dr， 0 ）; 
 
 ddlProdukt.DataSource = dt; 
 ddlProdukt.DataTextField =   Produktname; 
 ddlProdukt.DataValueField =   Produkt_id; 
 ddlProdukt.DataBind（）; 
 
} 

请更改您的下拉列表和其他人。它只是一个概念。

这是你以前的代码：

 public void FillActivityWaterStorage（）
 {
 try 
 {
 dt = Query.Guindy_ActivityWaterStorage_Population（）; 
 if（dt.Rows.Count> 0）
 {
 ddl_ActivityWaterStorage.Items.Clear（）; 
 ddl_ActivityWaterStorage.DataTextField =ActivityName; 
 ddl_ActivityWaterStorage.DataValueField =ActivityID; 
 
 ddl_ActivityWaterStorage.DataSource = dt; 
 ddl_ActivityWaterStorage.DataBind（）; 
 ddl_ActivityWaterStorage.Items.Insert（0，new ListItem（ -  SELECT--））; 
} 
 else 
 {ddl_SubActivityWaterStorage.Items.Insert（0，new ListItem（ -  SELECT--））; 
} 
} 
 catch {} 
} 

你在这里工作。 。 。在你的DropDownList2 jsut中添加项目就像你在dropdownList1中所做的那样

 ddl.Items.Insert（0， - ）; //只是像这样（如果下面的代码不起作用，则可选）

现在选择的ddl已更改：

 public void ddl_ActivityWaterStorage_SelectedChanged（Sender object，EventArguments e）
 {
 if（ddl_ActivityWaterStorage.SelectedValue == The2nditem）
 {
 ddl_SubActivityWaterStorage.DataSource = PopulateDataFromDatabase; 
 ddl_SubActivityWaterStorage.DataBind（）; 
} 
 else 
 {
 ddl_SubActivityWaterStorage.DataSource = null; 
 ddl_SubActivityWaterStorage.DataBind（）; 
} 
 
} 

希望它会起作用，如果出现错误或出错则发表评论，以便我再次检查代码:)

I have two drop down lists as DDL1 & DDL2. I have 3 items in DDL1, where the 1st item is --SELECT--. When I select the 22nd item in DDL1, the items of DDL2 gets populated from the database. But the problem is, when I select the --SELECT-- item in DDL1, the item which was previously selected in DDL2 remains as it is and does not removes.I want that when ever i select --SELECT-- in DDL1, DDL2 should get empty & when I select 1st or 2nd item from DDL1, then DDL2 should get populated from the database. Can any one please help ?

解决方案

Please try This...


link1

You need to do it on SelectedIndexChanged Event.

protected void ddlSparte_SelectedIndexChanged(object sender, EventArgs e)
    {
 DataRow dr = dt.NewRow();
            dr["Produktname"] = "...SELECT...";
            dr["Produkt_id"] = "0";
            dt.Rows.InsertAt(dr, 0);

            ddlProdukt.DataSource = dt;
            ddlProdukt.DataTextField = "Produktname";
            ddlProdukt.DataValueField = "Produkt_id";
            ddlProdukt.DataBind();

}

Please change your dropdownlist and others. Its just a concept.

this is your previous code:

public void FillActivityWaterStorage() 
{ 
  try 
    {  
    dt = Query.Guindy_ActivityWaterStorage_Population(); 
      if (dt.Rows.Count > 0) 
             {
               ddl_ActivityWaterStorage.Items.Clear(); 
               ddl_ActivityWaterStorage.DataTextField = "ActivityName";      
               ddl_ActivityWaterStorage.DataValueField = "ActivityID";  

               ddl_ActivityWaterStorage.DataSource = dt; 
               ddl_ActivityWaterStorage.DataBind();
               ddl_ActivityWaterStorage.Items.Insert(0, new ListItem("--SELECT--")); 
             } 
       else 
             { ddl_SubActivityWaterStorage.Items.Insert(0, new ListItem("--SELECT--"));
             } 
       } 
    catch { } 
 }

you do work around here. . . add item in your DropDownList2 jsut like you did in dropdownList1

ddl.Items.Insert(0,"--");//just like this(optional if the code below dont work) 

now for the ddl selected changed:

public void ddl_ActivityWaterStorage_SelectedChanged(Sender object,EventArguments e)
{
 if(ddl_ActivityWaterStorage.SelectedValue==The2nditem)
   {
    ddl_SubActivityWaterStorage.DataSource=PopulateDataFromDatabase;
    ddl_SubActivityWaterStorage.DataBind();
   }
 else
  {
   ddl_SubActivityWaterStorage.DataSource=null;
   ddl_SubActivityWaterStorage.DataBind();
  }

}

hope it will work,comment if got error or something wrong so I can check the code again :)

这篇关于下拉列表问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！