Use PHP to record the keywords that users enter the website through search engines_PHP tutorial

$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.com'=>'word',
     'google.com'=>'q',
     'sina.com.cn'=>'word',
     'sohu.com'=>'word',
     'msn.com'=>'q',
     'bing.com'=>'q',
     '163.com'=>'q',
     'yahoo.com'=>'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)";
}