ค้นหาหมายเลขของผลิตภัณฑ์ที่มีสีเป็น "สีแดง" และมีลักษณะที่เรียกว่า "ช้า"
Find the number of the products that have their color described as "red" and have a characteristic named "slow".
df_characteristics = pd.DataFrame(columns=['characteristic_id', 'characteristic_name'])
df_ref_colors = pd.DataFrame(columns=['color_code', 'color_description'])
df_products = pd.DataFrame(columns=['product_id', 'color_code'])
df_product_characteristics = pd.DataFrame(columns=['product_id', 'characteristic_id'])
df_products[(df_products['color_code'].isin(df_ref_colors[df_ref_colors['color_description'] == 'red']['color_code'])) & (df_products['product_id'].isin(df_product_characteristics[df_product_characteristics['characteristic_id'].isin(df_characteristics[df_characteristics['characteristic_name'] == 'slow']['characteristic_id'])]['product_id']))].shape[0]