利用ajax文件上传不成功
做之前不用异步直接测试HTML和PHP都是没问题的（说明下，我的后台用的PHP），但是当我采用AJAX异步上传的时候就出现问题了，本人新手，出于初级学习阶段，希望大家帮我指出下问题。
另外我想向WEB开发方向学习，目前只是熟悉了HTML，css，php（不过库函数没记到几个，基本都是w3c开着写代码），JS刚刚接触，学了一段时间后，我发现自己最基本HTTP协议都没有去看过，请问这样是不是有点本末倒置呢？希望有人能给指出个学习的顺序和重点，感激不尽。
下面上代码
html表单部分(表单具体内容太多，无关紧要，只贴了3个重要部分)
<html><head><title>上传页面</title><script type="text/javascript" src="js/upload.js"></script></head><body><form id="uploadform" method="post" ENCTYPE="multipart/form-data"><input onclick="show()" type="submit" value="上传" /></form><div style="width:200px;height:80px;background:yellow; float:left" id="uploadshow"></div></body>
function createAjax(){ var request=false; //window对象中有XMLHttpRequest存在就是非IE，包括（IE7，IE8） if(window.XMLHttpRequest){ request=new XMLHttpRequest(); if(request.overrideMimeType){ request.overrideMimeType("text/xml"); } //window对象中有ActiveXObject属性存在就是IE }else if(window.ActiveXObject){ var versions=['Microsoft.XMLHTTP', 'MSXML.XMLHTTP', 'Msxml2.XMLHTTP.7.0','Msxml2.XMLHTTP.6.0','Msxml2.XMLHTTP.5.0', 'Msxml2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP']; for(var i=0; i<versions.length; i++){ try{ request=new ActiveXObject(versions[i]); if(request){ return request; } }catch(e){ request=false; } } } return request; }var ajax=null;function show(){ ajax=createAjax(); ajax.open("post", "program_upload.php",true); ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); ajax.send(document.getElementById("uploadform").submit()); //指定异步处理显示对象 var obj_uploadshow=document.getElementById("uploadshow"); //回调函数 ajax.onreadystatechange=function(){ obj_uploadshow.innerHTML='uploading..'; if(ajax.readyState==4 && ajax.status==200){ var file=ajax.responseText; eval("var obj="+file); var id = obj.id; var program_contentadd = obj.program_contentadd; var program_date = obj.program_date; var program_team = obj.program_team; var program_title = obj.program_title; var program_author = obj.program_author; var program_add = obj.program_add; var program_type = obj.program_type; function upload_sql(){ ajax=createAjax(); ajax.open("POST", "program_upload_sql.php",true); ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); ajax.send('id='+id+'&program_contentadd='+program_contentadd+'&program_date='+program_date+'&program_team='+program_team+'&program_title='+program_title+'&program_author='+program_author+'&program_add='+program_add+'&program_type='+program_type); if(ajax.responseText==null){ var continue_send; continue_send=setTimeout("upload_sql()",1000);//每1秒检测一次文件是否上传成功 } var obj_uploadshow=document.getElementById("uploadshow"); ajax.onreadystatechange= function(){ if(ajax.readyState==4 && ajax.status==200 && ajax.responseText!=null){ var result=ajax.responseText; obj_uploadshow.innerHTML = "chenggong";//result; } } } } else{ alert("shibai"); } }}
<?phpinclude_once ("inc_connet_sql.php");$id=$_POST[id];$program_contentadd=$_POST[program_contentadd];$program_date=$_POST[program_date];$program_team=$_POST[program_team];$program_title=$_POST[program_title];$program_author=$_POST[program_author];$program_add=$_POST[program_add];$program_type=$_POST[program_type];if($_FILE[$program_contentadd]['error']=0){ if($_FILE[$program_add]['error']=0){ $sql="insert into program (program_main,program_id,program_contentadd,program_date,program_team,program_title,program_author,program_add,program_type)VALUES(' ','$id','$program_contentadd','$program_date','$program_team','$program_title','$program_author','$program_add','$program_type')"; if (mysql_query($sql,$link)){ echo "文件上传成功"; } else { die( 'Error:' . mysql_error() ); } mysql_close($link); }}?>