mySQL: Subquery to array?

Question

I am working on a slight complex (at least for me) mySQL query containing a subquery and it isn't going to well to be honest.

SELECT `products`.`id`, `product`.`price`, 
  ( SELECT `value` FROM (`productValues`) 
    WHERE `productValues`.`product` = 'product.id'
  ) as values 
FROM (`products`) WHERE`product`.`active` = 1

The current result looks like this:

Array
(
    [0] => Array
        (
            [id] => 1
            [active] => 1
            [price] => 1000
            [values] => 
        )
)

What I want is the values element to also become an array with all elements in the Values table which matches (WHERE productValues.product = product.id).

What am I doing wrong?

Answer 1

I'm not sure if you can return subqueries like this. A solution would be to use GROUP_CONCAT in your subsquery to concatinate all values to a string. Then, in the result, you can split this string into an array using explode.

update : Subquery can only match 1 row
source : http://dev.mysql.com/doc/refman/5.0/en/subquery-errors.html

Answer 2

SELECT p.id, p.price, pv.`value`
FROM products p
  JOIN  productValues pv
  ON p.product_id=pv.product
WHERE p.active = 1
ORDER BY p.id;

gives a table with one row for each pv.value (BTW, using reserved words like 'value' is not recommended). Ordering the output by p.id ensures that all the rows for a particular product are together. So, in the application layer, loop through your rows, changing product each time the p.id changes.

$old_id=NULL;
$datastructure=array();
while($arr=$result->fetch_assoc()){
  if($arr['id']!=$old_id){
    $datastructure[$arr['id']][price]=$arr['price'];
    $old_id=$arr['id'];
  }
  $datastructure[$arr['id']]['values'][]=$arr['value'];
}

The structure I've given is perhaps more flexible than the one you asked for in that it allows you to access a particular product through the array key.