Stackoverflow #24573343

gistfile1.php

                $product_ids_raw = $wpdb->get_results(
"SELECT wp_posts.ID, wp_posts.post_parent
FROM wp_posts  
INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)
INNER JOIN wp_postmeta AS mt1 ON (wp_posts.ID = mt1.post_id)
WHERE
    wp_posts.post_status = 'publish'
    AND  (mt1.meta_key = '_sale_price_dates_to' AND mt1.meta_value >= ".time().") 
    GROUP BY wp_posts.ID 
    ORDER BY wp_posts.post_title ASC LIMIT 0,12");
                
                $product_ids_on_sale = array();
                
                foreach ( $product_ids_raw as $product_raw ) 
                {
                    if(!empty($product_raw->post_parent))
                    {
                        if(!in_array($product_raw->post_parent, $product_ids_on_sale))
                        {
                            $product_ids_on_sale[] = $product_raw->post_parent;
                        }
                    }
                    else
                    {
                        $product_ids_on_sale[] = $product_raw->ID;  
                    }
                }
                
		$meta_query   = array();
		$meta_query[] = WC()->query->visibility_meta_query();
		$meta_query[] = WC()->query->stock_status_meta_query();
		$meta_query   = array_filter( $meta_query );