PHP用户输入到运行apache和PHP的Web Server的任何漏洞

Question

There is understandably a lot of emphasis on sanitizing user input handed off to PHP on a Web Server and numerous opinions on doing it.

Can someone please confirm there is no security problems with the following PHP code which may compromise the server through an exploit:

if($_SERVER['QUERY_STRING'] == "kjg68KGH$88@kjhik8768"){
   $_SERVER['QUERY_STRING']=NULL;
   do stuff
} else {
   $_SERVER['QUERY_STRING']=NULL;
   do other stuff
}

or

if($_POST['the-var'] == "kjg68KGH$88@kjhik8768"){
   $_POST=[];
   do stuff
} else {
  $_POST=[];
  do other stuff
}

If there is ( I do not see how there could be) then why? Thankyou.