我怎样才能找到过去90天内完成交易的客户百分比?

我正试图找到 百分比

我用的是亚马逊红移。

我试着写两个独立的查询,但是如果可能的话,我想合并它们。

/*
* Numerator (counting customers with purchases within 90 days of becoming members)
*/
SELECT 
    c.customer_id, 
    c.member_start
FROM
     (SELECT * FROM before_2012_data
      UNION ALL 
      SELECT  * FROM after_2012_data
     ) t
     LEFT JOIN customer_information c
     ON c.customer_id = t.customer_id
WHERE DATEDIFF(day, c.member_start, t.purchase_data) between 0 and 90 
GROUP BY  member_start, c.customer_id
ORDER BY member_start

/*
* Denominator (counting customers both with and without purchases within 90 days of becoming members)
*/
SELECT 
  c.customer_id, 
  c.member_start
FROM
     (SELECT * FROM before_2012_data
      UNION ALL 
      SELECT  * FROM after_2012_data
     ) t
     LEFT JOIN customer_information c
     ON c.customer_id = t.customer_id
GROUP BY  member_start, c.customer_id
ORDER BY member_start