在保存期间将＆lang = en更改为<= en

I have form with url input I enter the value http://www.sample.com/test.php?toto=1&lang=en but var &lange was changed to "<" in db I try something like this

 $url= htmlentities($url);
 $fieldValue = str_replace('lang;', 'lang', $url);

It save good but I looking better way to do this