如何用DropDownList控制TextBox的显示与隐藏???
一个DropDownList(ddl1),分三个下拉项(足球value=1、篮球value=2和游泳value=3). 
 三个TextBox(txt1,txt2,txt3).   
 如何实现用: 
 当DropDownList的value值为1时,txt1显示,txt2和txt3隐藏; 
 当DropDownList的value值为2时,txt2显示,txt1和txt3隐藏; 
 当DropDownList的value值为3时,txt3显示,txt1和txt2隐藏;   
 不会写这段代码,请高人帮忙写一下,高分相送:)
------解决方案--------------------selectchange事件中写显示还是隐藏
------解决方案--------------------selectchange事件中自己写一个Javascript的方法改变TextBox的style~~~ 
 styel.display =  "none "/ "block " 一个是不显示 一个是显示
------解决方案--------------------var sSelected = document.getElementById( " <%= ddl1.ClientID%>  ").value; 
 var oTxt1 = document.getElementById( " <%= txt1.ClientID%>  "); 
 var oTxt2 = document.getElementById( " <%= txt2.ClientID%>  "); 
 var oTxt3 = document.getElementById( " <%= txt3.ClientID%>  "); 
 if(sSelected ==  "1 ") 
 { 
 oTxt1.style.display =  "block "; 
 oTxt2.style.display =  "none "; 
 oTxt3.style.display =  "none "; 
 } 
 .... 
 其他的类似
------解决方案-------------------- <select id= "sel " onchange= "exchange(this.value) ">  
  <option value= "1 "> 足球 </option>  
  <option value= "2 "> 篮球 </option>  
  <option value= "3 "> 游泳 </option>  
  </select>  
  <br>  
  <input type=text id= "foot ">  
  <input type=text id= "bas ">  
  <input type=text id= "swing ">    
  <script>  
 function exchange(value) 
 { 
     var foot = document.getElementById( "foot "); 
     var bas= document.getElementById( "bas "); 
     var swing= document.getElementById( "swing "); 
     switch (value) 
      { 
           case   "1 ": 
              foot.style.display =  " "; 
              bas.style.display = swing.style.display =  "none "; 
              break; 
     } 
 } 
  </script>
------解决方案--------------------protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e) 
     { 
         if (DropDownList1.Items.FindByValue( "1 ").Selected == true) 
         { 
             TextBox1.Text = DropDownList1.SelectedItem.Text; 
             TextBox1.Visible = true; 
             TextBox2.Visible = false; 
             TextBox3.Visible = false; 
         } 
         if (DropDownList1.Items.FindByValue( "2 ").Selected == true) 
         { 
             TextBox2.Text = DropDownList1.SelectedItem.Text; 
             TextBox1.Visible = false; 
             TextBox2.Visible = true; 
             TextBox3.Visible = false; 
         } 
         if (DropDownList1.Items.FindByValue( "3 ").Selected == true) 
         { 
             TextBox3.Text = DropDownList1.SelectedItem.Text; 
             TextBox1.Visible = false; 
             TextBox2.Visible = false; 
             TextBox3.Visible = true; 
         } 
     }     
  <body>  
  <form id= "form1 " runat= "server ">  
      <div>  
      <table>  
          <tr>  
              <td>  
                  <asp:DropDownList ID= "DropDownList1 " runat= "server " AutoPostBack= "True " OnSelectedIndexChanged= "DropDownList1_SelectedIndexChanged "