PHP/MYSQLi/OOP public, protected, private function

I have created a public function (hoping that is the right one), I'm not really sure of the benefits and limitations, or best uses of each but... I need to run a function that will run for any person who accesses a certain page. The page is returning staff members and I want to display their title. public function getTitle( $id ) { global $params, $db; $db->query( "SELECT * FROM users WHERE `id` = '{$id}'" ); $db->assoc( $coreQuery ); return $this->data['title']; return true; } Previous code: public function getTitle( $id ) { global $params, $db; $coreQuery = $db->query( "SELECT * FROM users WHERE `id` = '{$id}'" ); $coreArray = $db->assoc( $coreQuery ); $return = $coreArray['title']; return $return; } I have used the above function but this is not returning anything in the echo. Have I done this wrong? Any help would be appreciated.