使用php记录用户通过搜索引擎进网站的关键词

$rfr = $_SERVER['HTTP_REFERER'];
//if(!$rfr) $rfr='http://'.$_SERVER['HTTP_HOST'];
if($rfr)
{
 $p=parse_url($rfr);
 parse_str($p['query'],$pa);
 $p['host']=strtolower($p['host']);
 $arr_sd_key=array(
     'baidu.'=>'word',
     'google.'=>'q',
     'sina..'=>'word',
     'sohu.'=>'word',
     'msn.'=>'q',
     'bing.'=>'q',
     '163.'=>'q',
     'yahoo.'=>'p'
     );
 $keyword='';
 $sengine=$p['host'];
 foreach($arr_sd_key as $se=>$kwd)
 {
  if(strpos($p['host'],$se)!==false)
  {
   $keyword=$pa[$kwd];
   $sengine=$se;
   break;
  }
 }
 $sql="insert into visit_log(domain,key_word,ct)";
}