sample query

gistfile1.txt

// first query, please make sure you modify this query to fit your purpose
$ids_array = array();

$result = mysql_query("SELECT id FROM table_name");

while($row = mysql_fetch_array($result))
{
    $ids_array[] = $row['id'];
}

// second query, please make sure you modify this query to fit your purpose
$result = mysql_query("SELECT product_id, sku, qty FROM table_name");
$result_array = array();
while($row = mysql_fetch_array($result))
{
    if (in_array($row['product_id'], $ids_array)) {
        $row['qty'] = 0; 
    }

    $result_array[] = $row;
}