gistfile1.txt

def self.best_selling
      self.find_by_sql 'SELECT COALESCE(SUM(variants.num), 0) AS num, sellor_products.*
                        FROM sellor_variants
                        LEFT JOIN sellor_products ON sellor_products.id = sellor_variants.sellor_product_id
                        LEFT JOIN
                          (
                            SELECT sellor_variant_id AS id, COALESCE(SUM(quantity), 0) AS num
                            FROM sellor_order_items
                            GROUP BY sellor_variant_id
                            ORDER BY num DESC
                          ) variants
                          ON sellor_variants.id = variants.id
                          GROUP BY sellor_products.id
                          ORDER BY num DESC
                          LIMIT 5'
    end