TPC-DS Q87

SELECT
  COUNT(*)
FROM (
  (
    SELECT DISTINCT
      c_last_name,
      c_first_name,
      d_date
    FROM store_sales, date_dim, customer
    WHERE
      store_sales.ss_sold_date_sk = date_dim.d_date_sk
      AND store_sales.ss_customer_sk = customer.c_customer_sk
      AND d_month_seq BETWEEN 1203 AND 1203 + 11
  )
  EXCEPT
  (
    SELECT DISTINCT
      c_last_name,
      c_first_name,
      d_date
    FROM catalog_sales, date_dim, customer
    WHERE
      catalog_sales.cs_sold_date_sk = date_dim.d_date_sk
      AND catalog_sales.cs_bill_customer_sk = customer.c_customer_sk
      AND d_month_seq BETWEEN 1203 AND 1203 + 11
  )
  EXCEPT
  (
    SELECT DISTINCT
      c_last_name,
      c_first_name,
      d_date
    FROM web_sales, date_dim, customer
    WHERE
      web_sales.ws_sold_date_sk = date_dim.d_date_sk
      AND web_sales.ws_bill_customer_sk = customer.c_customer_sk
      AND d_month_seq BETWEEN 1203 AND 1203 + 11
  )
) AS cool_cust;