how many characteristics does the product name 'sesame' have?
SELECT count ( * )  FROM products AS t1 JOIN product_characteristics AS t2 ON t1.product_id   =   t2.product_id WHERE t1.product_name   =   "sesame"
number of characteristics for a product refers to COUNT(*) from a join between products and product_characteristics tables; product named 'sesame' refers to WHERE product_name = 'sesame';