mas o menos asi
Código PHP:
$query="select * from products WHERE activo =\"1\" AND oferta=\"si\"";
$result=mysql_query($query);
while ($row = mysql_fetch_array($result))
{
// Miro que la categoria este activa
$categoryid = $row['categoryid'];
$querycat="select * from category WHERE $categoryid =\"$categoryid\"";
$resultcat=mysql_query($querycat);
while($rowcat = mysql_fetch_array($resultcat)){
$activocat = $rowcat['activo'];
echo $activocat;
}
echo $categoryid;
}