this is my code for this purpose
$sql_s="SELECT column FROM products LIMIT 10 WHERE id_product={$id}";
LIMIT 10
should be after the WHERE
clause.
$sql_s = "SELECT column FROM products WHERE id_product={$id} LIMIT 0, 10";
Edit 1
This link helps with debugging MySQLi
(assuming your are using that).
http://jason.pureconcepts.net/2013/04/common-debugging-php-mysql/