Dropdownlist如何在ASP.net中将第一个值设置为空值 [英] Dropdownlist how to set the first value as null value in ASP.net

问题描述

我有一个下拉绑定，总是从绑定数据中选择第一个值，如何将第一个值设置为空值，任何1可以帮助我

  void  dropdown_bind（）
 {
 
 adp =  new  SqlDataAdapter（  sp_dropdownbind ，con）; 
 adp.SelectCommand.CommandType = CommandType.StoredProcedure; 
 ds =  new  DataSet（）; 
 adp.Fill（ds）; 
 
 ddlTypeid.DataTextField =  名称; 
 ddlTypeid.DataSource = ds.Tables [ 0 ]; 
 ddlTypeid.DataBind（）; 
 
 ddlproductid.DataTextField =   ProductName; 
 ddlproductid.DataSource = ds.Tables [ 1 ]; 
 ddlproductid.DataBind（）; 
 
 
} 
 

解决方案

< ; asp：dropdownlist id =   DropDownList2 runat =    server appenddatabounditems =   true xmlns：asp =  ＃unknown > ;  
 
< asp：listitem selected =   True text =    value  = < span class =code-string>  >  < /   asp：listitem  >  
 
 < /   asp：下拉列表 >  

I had a dropdown bind which always selects the first value from the bound data, how to set the first value as "null value" can any 1 helps me

void dropdown_bind()
  {

      adp = new SqlDataAdapter("sp_dropdownbind", con);
      adp.SelectCommand.CommandType = CommandType.StoredProcedure;
      ds = new DataSet();
      adp.Fill(ds);

      ddlTypeid.DataTextField = "Name";
      ddlTypeid.DataSource = ds.Tables[0];
      ddlTypeid.DataBind();

      ddlproductid.DataTextField = "ProductName";
      ddlproductid.DataSource = ds.Tables[1];
      ddlproductid.DataBind();


  }

解决方案

<asp:dropdownlist id="DropDownList2" runat="server" appenddatabounditems="true" xmlns:asp="#unknown">
 
<asp:listitem selected="True" text="" value=""></asp:listitem>
 
</asp:dropdownlist>

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