How to make SQL query with Magento

Question

This is part of the aw blog module. I have 2 tables.

aw_blog
post_id | tags
1 tag1
2 tag2
3 tag3

aw_blog_post_cat
cat_id | post_id
1 1
1 3
2 3

I have that SQL statement and i am trying to do it with magento way:

SELECT `aw_blog`.`tags` FROM `aw_blog_post_cat` RIGHT JOIN  `aw_blog` on `aw_blog`.`post_id`=`aw_blog_post_cat`.`post_id` WHERE `aw_blog_post_cat`.`cat_id`=1

I tried something like that:

$collection = Mage::getModel('blog/blog')->getCollection()
->getSelect()->joinRight(array("post_cat" => $this->getTable('aw_blog_post_cat')), 'main_table.post_id = post_cat.post_id', array()); 

from that link But with no luck. There is no model implemented for aw_blog_post_cat table

Answer 1

I didn't test because I don't have the module installed on a Magento installation but I checked the source code and I am not sure if it is latest one. You have in the collection of the Blog class AW_Blog_Model_Mysql4_Blog_Collection a method which helps to filter the content based on the category id

class AW_Blog_Model_Mysql4_Blog_Collection
...
public function addCatFilter($catId)
{
    $this->getSelect()->join(
        array('cat_table' => $this->getTable('post_cat')),
        'main_table.post_id = cat_table.post_id',
        array()
    )
    ->where('cat_table.cat_id = ?', $catId);

    return $this;
}

Then you can use in your code that:

$collection = Mage::getModel('blog/blog')->getCollection()
    ->addCatFilter(1);

$items = $collection->getItems();

So now you get all post items.

Answer 2

The Fishpig blog has an excellent article about writing custom queries. It explains in detail how to get the query resources and tablenames.

In your case it would be something like this

$resource = Mage::getSingleton('core/resource');
$read = $resource->getConnection('core_read');

$results = $read->fetchAll("SELECT * FROM {$resource->getTableName('blog/post_cat')}"); // change the query to your needs

var_dump($results);