mysql - 从 2 个表中以及指定日期之间选择最新日期

Question

我有一个查询，其中我获取特定日期范围内的记录的总和。现在我尝试在每个日期范围内包含一列的最新日期。

SQL fiddle :

http://sqlfiddle.com/#!9/2b486/6

查询:

SELECT
Contract.contract_length,
SUM(
  CASE WHEN
    Contract.created BETWEEN '2013-01-01 00:00:00' AND '2013-03-31 23:59:59'
  THEN 1 ELSE 0 END
) as rental_count_Q1_2013,
SUM(
  CASE WHEN
    Contract.created BETWEEN '2013-01-01 00:00:00' AND '2013-03-31 23:59:59'
    AND termination_date BETWEEN '2013-01-01 00:00:00' AND NOW()
  THEN 1 ELSE 0 END
) as terminated_count_Q1_2013,
SUM(
  CASE WHEN
    Contract.created BETWEEN '2013-01-01 00:00:00' AND '2013-03-31 23:59:59'
    AND(
      Data1Payout.payout_date BETWEEN '2013-01-01 00:00:00' AND NOW()
      OR Data2Payout.payout_date BETWEEN '2013-01-01 00:00:00' AND NOW()
    )
  THEN 1 ELSE 0 END
) as customer_payouts_Q1_2013,
SUM(
  CASE WHEN
    Contract.created BETWEEN '2013-04-01 00:00:00' AND '2013-06-30 23:59:59'
  THEN 1 ELSE 0 END
) as rental_count_Q2_2013,
SUM(
  CASE WHEN
    Contract.created BETWEEN '2013-04-01 00:00:00' AND '2013-06-30 23:59:59'
    AND termination_date BETWEEN '2013-04-01 00:00:00' AND NOW()
  THEN 1 ELSE 0 END
) as terminated_count_Q2_2013,
SUM(
  CASE WHEN
    Contract.created BETWEEN '2013-04-01 00:00:00' AND '2013-06-30 23:59:59'
    AND(
      Data1Payout.payout_date BETWEEN '2013-04-01 00:00:00' AND NOW()
      OR Data2Payout.payout_date BETWEEN '2013-04-01 00:00:00' AND NOW()
    )
  THEN 1 ELSE 0 END
) as customer_payouts_Q2_2013

FROM contracts AS Contract
LEFT OUTER JOIN (
  SELECT id, customer_id, payments_made, termination_date FROM terminations
) AS Termination on Termination.customer_id = Contract.customer_id
LEFT OUTER JOIN (
  SELECT id, customer_id, payout_date FROM datasource_1_payouts
) AS Data1Payout on Data1Payout.customer_id = Contract.customer_id
LEFT OUTER JOIN (
  SELECT id, customer_id, payout_date FROM datasource_2_payouts
) AS Data2Payout on Data2Payout.customer_id = Contract.customer_id
GROUP BY Contract.contract_length

这将返回每个季度的租金、这些租金的终止以及这些租金的支付计数，并按契约(Contract)期限进行分组。

contract_length | rental_count_Q1_2013 | terminated_count_Q1_2013 | customer_payouts_Q1_2013 | rental_count_Q2_2013 | terminated_count_Q2_2013 | customer_payouts_Q2_2013
24              |           2          |           1              |           1              |           1          |           0              |           1
36              |           2          |           1              |           1              |           2          |           0              |           2
48              |           1          |           1              |           0              |           2          |           1              |           1

我还需要获取每个季度的最后付款日期。 IE。上次付款日期是根据 2013 年第一季度创建的契约(Contract)进行的。付款也存储在 2 个单独的表中。

我尝试过的:

使用 MAX():

CASE WHEN
    Contract.created BETWEEN '2013-01-01 00:00:00' AND '2013-03-31 23:59:59'
    AND Data1Payout.payout_date BETWEEN '2013-04-01 00:00:00' AND NOW()
    AND MAX(Data1Payout.payout_date) > MAX(Data2Payout.payout_date)
    THEN MAX(Data1Payout.payout_date) ELSE MAX(Data2Payout.payout_date) END
as last_payout_date_Q1_2013

这不起作用，因为所有支付日期都包含在每个结果中，因此 MAX() 始终是最新的总体结果。

工作解决方案:

MAX(
    CASE WHEN Contract.created BETWEEN '2013-01-01 00:00:00' AND '2013-03-31 23:59:59'
    THEN GREATEST(IFNULL(Data1Payout.payout_date, '0000-00-00'), IFNULL(Data2Payout.payout_date, '0000-00-00'))
    ELSE NULL END
) AS last_payout_date_Q1_2013

Answer 1

您将 MAX 函数放在错误的位置。实际上，它与其他CASE语句相同。
由于您的查询太长，我将做一个简单的解释，希望对您有所帮助。

SELECT 
    SUM(
    CASE WHEN x = 'yes'
    THEN 1 ELSE 0
    END) AS SUM_NUMBER, --terminated_count_Q1_2013 for example
    MAX(
    CASE WHEN x = 'yes'
    THEN yourdatecolumn
    ELSE NULL END) AS MAX_DATE --last_payout_date_Q1_2013 for example
FROM yourtable

我希望您知道如何在您自己的查询中实现此功能。