Magento: How to get attribute values used in products

Question

How I can get attribute values for some attribute that are used at least in one product?

Answer 1

I needed a function to get all the values for the atribute, that are used in a specific category. I wrote this function which is not exactly what was needed by the author of the question but maybe it will help somebody.

    private function _getUsedAttribute($attributeCode, $categoryName)
{
    $category = Mage::getModel('catalog/category')->loadByAttribute('name', $categoryName);
    $attributeModel = Mage::getSingleton('eav/config')->getAttribute('catalog_product', $attributeCode);

    $sql = "SELECT DISTINCT(cpev.value)
            FROM catalog_product_entity_varchar cpev
            LEFT JOIN catalog_category_product ccp ON ccp.product_id = cpev.entity_id
            WHERE 
                cpev.attribute_id = {$attributeModel->getId()} AND
                ccp.category_id = {$category->getId()} AND
                cpev.value IS NOT NULL AND
                cpev.value <> ''";

    $data = $this->_getReadConnection()->fetchAll($sql);
    $usedAttributes = array(); 

    foreach ($data as $_item) {
        $_ids = explode(',', $_item['value']);
        foreach ($_ids as $_id) {
            if (empty($usedAttributes[$_id])) {                    
                $usedAttributes[$_id] = $attributeModel->getSource()->getOptionText($_id);
            }
        }            
    }
    natsort($usedAttributes);

    return $usedAttributes;  
}    

/**
 * read connection     
 */
protected function _getReadConnection() {
    return Mage::getSingleton('core/resource')->getConnection('core_read');
}  


print_r($this->_getUsedAttribute('device_brand', 'Phones'));

Array ( [204] => Acer [40] => Alcatel [237] => Allview [128] => Apple [225] => Asus ... )