产生错误输出的日期的 MIN 和 MAX

Question

我有付款数据，我想根据不同的付款类型和 COUNT 次付款和调整显示 MIN 和 MAX 日期。

CREATE TABLE Payment
(BillingId int, PaymentId int, PaymentDate date, PaymentType varchar(50), PaymentBy varchar(50));

INSERT INTO Payment
VALUES
(12345, 1, '2022-02-02', 'payment', 'Insurance'),
(12345, 2, '2022-02-02', 'adjustment', 'Insurance'),
(67890, 3, '2022-01-19', 'payment', 'Insurance'),
(67890, 4, '2022-01-19', 'adjustment', 'Insurance'),
(67890, 5, '2022-01-19', 'payment', 'Insurance'),
(67890, 6, '2022-02-02', 'payment', 'Client')

SELECT * FROM Payment

BillingId	PaymentId	PaymentDate	PaymentType	PaymentBy
12345	1	2022-02-02	payment	Insurance
12345	2	2022-02-02	adjustment	Insurance
67890	3	2022-01-19	payment	Insurance
67890	4	2022-01-19	adjustment	Insurance
67890	5	2022-01-19	payment	Insurance
67890	6	2022-02-02	payment	Client

我需要按 BillingId 对数据进行分组并显示 6 个日期（在其中发布，特别是在 MIN 中）和 4 个总计数（它们产生正确的输出）：

保险付款的最迟日期
保险公司付款的最大日期
MIN 客户付款日期
客户付款的最大日期
MIN 调整日期
进行调整的最大日期
COUNT 笔所有付款（未经调整）
保险公司支付了 COUNT 笔款项
客户支付了 COUNT 笔款项
COUNT 个调整量

P.S。例如，如果保险公司只支付了 1 笔款项，那么 MIN 和 MAX 日期应该相同。

我的代码：

SELECT p.BillingId, 

        MIN(CASE WHEN p.PaymentBy = 'Insurance' AND p.PaymentType != 'adjustment' THEN p.PaymentDate ELSE '' END) AS EarliestDateInsurancePaid,
        MAX(CASE WHEN p.PaymentBy = 'Insurance' AND p.PaymentType != 'adjustment'  THEN p.PaymentDate ELSE '' END) AS LatestDateInsurancePaid,
        MIN(CASE WHEN p.PaymentBy = 'Client' AND p.PaymentType != 'adjustment' THEN p.PaymentDate ELSE '' END) AS EarliestDateClientPaid,
        MAX(CASE WHEN p.PaymentBy = 'Client' AND p.PaymentType != 'adjustment' THEN p.PaymentDate ELSE '' END) AS LatestDateClientPaid,
        MIN(CASE WHEN p.PaymentType = 'adjustment' THEN p.PaymentDate ELSE '' END) AS EarliestAdjustmentDate,
        MAX(CASE WHEN p.PaymentType = 'adjustment' THEN p.PaymentDate ELSE '' END) AS LatestAdjustmentDate,

        COUNT(CASE WHEN p.PaymentType != 'adjustment' THEN p.PaymentType END) AS TotalAmountOfPayments,
        COUNT(CASE WHEN p.PaymentBy = 'Insurance' AND p.PaymentType != 'adjustment' THEN p.PaymentBy END) AS AmountOfInsurancePayments,
        COUNT(CASE WHEN p.PaymentBy = 'Client' AND p.PaymentType != 'adjustment' THEN p.PaymentBy END) AS AmountOfClientPayments, 
        COUNT(CASE WHEN p.PaymentType = 'adjustment' THEN p.PaymentType END) AS AmountOfAdjustments
            
FROM Payment AS p
GROUP BY p.BillingId

上述查询的输出：

BillingId	EarliestDateInsurancePaid	LatestDateInsurancePaid	EarliestDateClientPaid	LatestDateClientPaid	EarliestAdjustmentDate	LatestAdjustmentDate	TotalAmountOfPayments	AmountOfInsurancePayments	AmountOfClientPayments	AmountOfAdjustments
12345	1900-01-01	2022-02-02	1900-01-01	1900-01-01	1900-01-01	2022-02-02	1	1	0	1
67890	1900-01-01	2022-01-19	1900-01-01	2022-02-02	1900-01-01	2022-01-19	3	2	1	1

我需要的输出：

BillingId	EarliestDateInsurancePaid	LatestDateInsurancePaid	EarliestDateClientPaid	LatestDateClientPaid	EarliestAdjustmentDate	LatestAdjustmentDate	TotalAmountOfPayments	AmountOfInsurancePayments	AmountOfClientPayments	AmountOfAdjustments
12345	2022-02-02	2022-02-02	1900-01-01	1900-01-01	2022-02-02	2022-02-02	1	1	0	1
67890	2022-01-19	2022-01-19	2022-02-02	2022-02-02	2022-01-19	2022-01-19	3	2	1	1

Answer 1

您对 max(case when..else '' end... 的使用导致了 1900 日期，因为 max 函数不会忽略 empty/zero 长度的字符串，它们被转换为日期。使用 NULL（或没有 ELSE 部分，默认为 NULL）； MAX 和许多其他聚合函数忽略 NULL 值。

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