UPDATE 语句的语法错误。
updateshow.asp:   
  <%@LANGUAGE= "VBScript "   codepage= "936 "%>  
  <%if   session( "admin ") <>  " "   then%>  
  <!--#include   file= "conn.asp "-->  
  <% 
 set   rs=server.createobject( "adodb.recordset ") 
 id=Request.QueryString( "id ") 
 sql= "select   *   from   main   where   id= "&id 
 rs.open   sql,conn,2,3 
 %>  
  <html>  
  <head>  
  <title> 留言本-填写留言 </title>  
  <link   href= "style.css "   rel= "stylesheet "   type= "text/css ">  
  </head>  
  <body>  
  <form   action= "update.asp "   method= "post "   name= "add ">  
  <input   type= "hidden "   name= "id "   value= " <%=Request.QueryString( "id ")%>  "/>  
        <table   width= "450 "   border= "0 "   align= "center "   cellpadding= "2 "   cellspacing= "0 ">  
              <tr>  
                    <td   height= "40 "   colspan= "2 "   align= "center ">  <span   class= "text3 ">  <strong> 留言本-填写留言 </strong>  </span>  </td>  
              </tr>  
              <tr>  
                    <td   width= "124 ">  <P   style= "MARGIN-TOP:   2px;   MARGIN-LEFT:   80px "> 姓名 </p>  </td>  
                    <td   width= "318 ">  <input   name= "user "   type= "text "   id= "user "   value= " <%=rs( "user ")%>  ">  </td>  
              </tr>  
              <tr>  
                    <td>  <P   style= "MARGIN-TOP:   2px;   MARGIN-LEFT:   80px "> QQ号 </p>  </td>  
                    <td>  <input   name= "qq "   type= "text "   value= " <%=rs( "qq ")%>  ">  </td>  
              </tr>  
              <tr>  
                    <td>  <P   style= "MARGIN-TOP:   2px;   MARGIN-LEFT:   80px "> 邮件 </p>  </td>  
                    <td>  <input   name= "email "   type= "text "   value= " <%=rs( "email ")%>  ">                    </td>  
              </tr>  
              <tr>  
                    <td   valign= "top ">  <P   style= "MARGIN-TOP:   5px;   MARGIN-LEFT:   80px "> 内容 </p>  </td>  
                    <td>  <textarea   name= "content "   cols= "30 "   rows= "5 ">  <%=rs( "content ")%>  
                    </textarea>  </td>