optimize query: get all votes from user's item - php

Question

i did it my way because i'm very bad getting results from two tables...
Basically, first i get all the id items that correspond to the user, and then i calculate the ratings of each item.
But, there is two different types of object item, so i do this 2 times: show you:
function votos_usuario($id){
// $previa = "SELECT id FROM preguntas WHERE id_usuario = '$id'";
// $r_previo = mysql_query($previa);
// $ids_p = '0, ';
// while($items_previos = mysql_fetch_array($r_previo)){
// $ids_p .= $items_previos['id'].", ";
// //echo "ids pregunta usuario: ".$items_previos['id']."<br>";
// }
// $ids = substr($ids_p,0,-2);
// //echo $ids;
//
// $consulta = "SELECT valor FROM votos_pregunta WHERE id_pregunta IN ( $ids )";
// //echo $consulta;
//
// $resultado = mysql_query($consulta);
// $votos_preguntas = 0;
// while($voto = mysql_fetch_array($resultado)){
// $votos_preguntas = $votos_preguntas + $voto['valor'];
// }
$votos_preguntas= 0;
$votos_preguntas = mysql_query("SELECT SUM(valor) FROM votos_pregunta WHERE id_pregunta IN (SELECT id FROM preguntas WHERE id_usuario = '$id')");
$previa_r = "SELECT id FROM recetas WHERE id_usuario = '$id'";
$r_previo_r = mysql_query($previa_r);
$ids_r = '0, ';
while($items_previos_r = mysql_fetch_array($r_previo_r)){
$ids_r .= $items_previos_r['id'].", ";
//echo "ids pregunta usuario: ".$items_previos['id']."<br>";
}
$ids = substr($ids_r,0,-2);
$consulta_b = "SELECT valor FROM votos_receta WHERE id_receta IN ( $ids )";
//echo $consulta;
$resultado_b = mysql_query($consulta_b);
$votos_recetas = 0;
while($voto_r = mysql_fetch_array($resultado_b)){
$votos_recetas = $votos_recetas + $voto_r['valor'];
}
$total = $votos_preguntas + $votos_recetas;
return $total;
}
As you can si this is two much.. O(n^2)
Feel like thinking?
thanks!

Answer 1

You can do this for both:
$votos_preguntas = mysql_query("SELECT SUM(valor) FROM votos_pregunta WHERE id_pregunta IN (SELECT id FROM preguntas WHERE id_usuario = '$id')");
If votos_pregunta and votos_rectas have the same structure, I would only have it as one table with a newly added type column that could be either rectas or preguntas. Then you need to only do one statement for $total.