Is it correct to clear variables in PHP this way?

Question

PHP

Good day. Is it correct to clear variables in this way? If not, then why and how, please explain to a novice php developer.
$ora = "(au.payment LIKE '%" . $system->cleanvars($_SESSION['advs']['payment'][0]) . "%') AND ";

Answer 1

No, not right.
Variables do not need to be cleared. AT ALL . You just need to work correctly with the library for the DBMS.
To work with the request as with a string is also not correct.
Learn: www.php.net/manual/en/pdostatement.bindvalue.php