How to use SQL in Magento modules

Question

I have the follow SQL that I want to execute from a custom module:

SELECT c2.value
FROM catalog_category_product c1
INNER JOIN catalog_category_entity_varchar c2 ON (c1.category_id = c2.entity_id)
INNER JOIN catalog_product_entity c3 ON (c1.product_id = c3.entity_id)
WHERE c2.attribute_id = (SELECT attribute_id FROM eav_attribute WHERE attribute_code = 'name' AND entity_type_id = 3)
AND c3.entity_id = PRODUCT_ID_HERE

I am new on this and, from what I read, I should be able to use collections and commands like getSelect(), but I can't figure out a way to "convert" my SQL query into this format.

How can I do that? Or where can I read more about it?

Thanks!

---

REAL EXAMPLE:

To be more clear, I need to modify an extension in order to bring product categories field in a specific report. Editing .phtml files I am able to do somethings like this:

$product_id = PRODUCT_ID_HERE;
$product = Mage::getModel('catalog/product')->load($product_id);
$cats = $product->getCategoryIds();

foreach ($cats as $category_id) {
   $_cat = Mage::getModel('catalog/category')->load($category_id);
   echo $_cat->getName();
}

But with that I am changing just the Frontend. The better solution would be to edit the extension Model to do something like what they already have:

$itemTable = Mage::helper('advancedreports/sql')->getTable('sales_flat_order_item');
$this->getSelect()
   ->join(
      array('item' => $itemTable),
      "(item.order_id = main_table.entity_id AND item.parent_item_id IS NULL)",
      array()
   );

But I can't figure out how to "convert" my SQL query into this Model format...

Answer 1

You can do it following way.

$product_id = 1;

$db   = Mage::getSingleton('core/resource')->getConnection('core_read');
$subselect = $db->select()
    ->from('eav_attribute', array('attribute_id'))
    ->where('attribute_code = ?', 'name')
    ->where('entity_type_id = ?', 3);

$sql = $db->select()->from( 'catalog_category_product', array() )
    ->joinInner(
        'catalog_category_entity_varchar',
        'catalog_category_product.category_id = catalog_category_entity_varchar.entity_id',
        array('value')
    )
    ->joinInner(
        'catalog_product_entity',
        'catalog_category_product.product_id = catalog_product_entity.entity_id',
        array()
    )
    ->where("catalog_category_entity_varchar.attribute_id = ($subselect)")
    ->where("catalog_product_entity.entity_id=?", $product_id);
// print sql
echo $sql->__toString();

// print data
$data = $db->fetchAll($sql);
print_r($data);