SET @rank = 0;

SELECT
  company_name,
  sale_date,
  total_amount,
  day_rank
FROM (
  SELECT
    company_name,
    sale_date,
    total_amount,
    @rank := IF( @comp_id = company_id, @rank + 1, 1) AS day_rank,
    @comp_id := company_id
  FROM
    company_sales
  ORDER BY
    company_id, total_amount DESC) rankings
ORDER BY
  company_name, day_rank