Hur man uppdaterar flera kolumner i mysql med php

 $sql = "UPDATE `product_list` SET 
       `product_name` = '$product_name', 
       `product_category` = '$product_category', 
       `product_price` = '$product_price', 
       `product_description` = '$product_description', 
       `product_size_category` = '$size_category' 
  where clause..... (if required) ";