Db::getInstance()->insert() shows no error, doesn't work - prestashop

Question

I am inserting data into database. It doesn't get inserted. If I do the same via raw SQL it works. Doesn't show any errors too.
$products = Context::getContext()->cart->getProducts();
foreach($products as $product){
$id_product = $product['id_product'];
$is_allowed = (bool) Db::getInstance()->execute("SELECT available_for_order FROM ps_product WHERE id_product=".$id_product); // is product availabe for order when stock is null or zero.
// $sql = 'INSERT INTO `cart_log` (`id_product`,`ids_product_attribute`,`stock`,`reference`,`available_for_order`,`created_at`)
// VALUES (' . $id_product. ', ' . $product['id_product_attribute'] . ',' . $product['stock_quantity'] . ', ' . $product['reference'] .','. $is_allowed .', NOW())';
// die($sql);
$data= array(
'id_product' => (string) $id_product,
'ids_product_attribute' =>(string) $product['id_product_attribute'],
'stock' =>(string) $product['stock_quantity'],
'reference' =>(string) $product['reference'],
'available_for_order' =>(int) $is_allowed,
'created_at' => 'NOW())'
);
echo "<pre>";
print_r($data);
echo "</pre>";
$result= Db::getInstance()->insert('cart_log',$data);
}

Answer 1

try replace :
$is_allowed = (bool) Db::getInstance()->execute("SELECT available_for_order FROM ps_product WHERE id_product=".$id_product); // is product availabe for order when stock is null or zero.
by
$is_allowed = (bool) Db::getInstance()->getValue("SELECT available_for_order FROM ps_product WHERE id_product=".$id_product); // is product availabe for order when stock is null or zero.
execute() will return true or false if the request has correctly been executed, but not the request result. getValue() will return you request result.
There is also getRow() to get multiple elements of a same line, and executeS() to get multiple lines.
Regards