Tady máte problém s uvozovkami. Změnit
$sqlCmd = sprintf("UPDATE account.account SET coins = coins +100 WHERE id = '.$_SESSION['user_id'].'"
s
$sqlCmd = "UPDATE account.account SET coins = coins +100 WHERE id = '".$_SESSION['user_id']."'"
Tady máte problém s uvozovkami. Změnit
$sqlCmd = sprintf("UPDATE account.account SET coins = coins +100 WHERE id = '.$_SESSION['user_id'].'"
s
$sqlCmd = "UPDATE account.account SET coins = coins +100 WHERE id = '".$_SESSION['user_id']."'"