如何计算 table 中的 MAX not NULL？

Question

如何在不为 NULL 的情况下获得 MAX 3 个月？

因此我需要 UserId、UserAgreementId 和 MAX Not NULL 以及 Group BY UserId

month	Id	UserId	UserAgreementId	SubsriptionDate	Amount
1	NULL	NULL	NULL	NULL	NULL
2	12	222	33333	2020-02-02 00:00:00.000	40000
3	NULL	NULL	NULL	NULL	NULL
4	13	222	33333	2020-04-03 00:00:00.000	5000
5	NULL	NULL	NULL	NULL	NULL
6	15	222	33333	2020-06-04 00:00:00.000	7000
7	16	222	33333	2020-07-02 00:00:00.000	8000
8	17	222	33333	2020-08-09 00:00:00.000	4000
9	NULL	NULL	NULL	NULL	NULL
10	NULL	NULL	NULL	NULL	NULL
11	NULL	NULL	NULL	NULL	NULL
12	NULL	NULL	NULL	NULL	NULL

因为结果必须是这样的

UserId	UserAgreementId	MAX
222	33333	3

Table AgreementId 在行中有 SubsriptionDate，我需要计算最大不为空的期间 Amount

UserAgreementId	SubsriptionDate	Amount
33333	2020-02-02 00:00:00.000	40000
33333	2020-04-03 00:00:00.000	5000
33333	2020-06-04 00:00:00.000	7000
33333	2020-07-02 00:00:00.000	8000
33333	2020-08-09 00:00:00.000	4000

Answer 1

您要查询的内容对于查询来说太复杂了 - 运行需要很长时间。

例如，我在下面整理了一份草稿，它几乎为每个用户提供了最长的持续时间，但它引用了相同的 table 5 次。

这几乎不可读，令人费解，并且会给服务器带来比你想要的更多的负担。

取而代之的是获取记录并用更合适的table编程语言处理它们。

SELECT t.user_id, MAX(t.monthsTotal - s.monthsTotal + 1) AS longestDuration
FROM (SELECT a.*, YEAR(a.subscriptionDate) * 12 + a.month AS monthsTotal
     FROM table_name) as t
INNER JOIN (SELECT a.*, YEAR(a.subscriptionDate) * 12 + a.month AS monthsTotal
    FROM table_name AS a
    LEFT OUTER JOIN table_name AS preceeding
        ON a.user_id = preceeding.user_id
        AND YEAR(a.subscriptionDate) * 12 + a.month = YEAR(preceeding.subscriptionDate) * 12 + preceeding.month + 1
    WHERE preceedingMonth.id IS NULL) AS s
    ON t.user_id = s.user_id
    AND t.monthsTotal >= s.monthsTotal
LEFT OUTER JOIN (SELECT a.*, YEAR(a.subscriptionDate) * 12 + a.month AS monthsTotal
    FROM table_name AS a
    LEFT OUTER JOIN table_name AS preceeding
        ON a.user_id = preceeding.user_id
        AND YEAR(a.subscriptionDate) * 12 + a.month = YEAR(preceeding.subscriptionDate) * 12 + preceeding.month + 1
    WHERE preceedingMonth.id IS NULL) AS dummy
    ON t.user_id = dummy.user_id
    AND dummy.monthsTotal > s.monthsTotal
    AND t.monthsTotal > dummy.monthsTotal
WHERE dummy.id IS NULL
GROUP BY t.user_id

如何计算 table 中的 MAX not NULL？

How to calculate MAX not NULL in table?

sql

sql-server

max