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我正在使用审计表来查找在“2011-01-01 08:00:00.000”上运行的单个破坏性 SQL 语句的记录。您可以假设每个 MyTable 记录在脚本运行的这一天只更新一次。此 SQL 可能由用户运行，无法检索。每次对 MyTable 进行更改时，新值的审计跟踪都会存储在 AuditMyTable 中。

我的原始表架构：

MyTable(AccountId int PK, Amount int)

我的 MyTable 架构的审计跟踪表：

AuditMyTable(AccountId int, Amount int, AuditDate datetime)

我的问题是如何从 AuditMyTable 针对自身编写 SQL 连接，以便我可以取回以下数据：

AuditMyTable.AccountId, AuditMyTable.Amount as [NullAmount], AuditMyTablePrevious.Amount as [PreviousNotNullAmount]

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1 回答 1

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首先，你必须得到你的序列（我正在根据你的日期制作一个，假设它们严格增加）：

SELECT AccountId, cur.AuditDate AS cur_AuditDate, MAX(prev.AuditDate) AS prev_AuditDate
FROM AuditMyTable AS cur
LEFT JOIN AuditMyTable AS prev
    ON prev.AccountId = cur.AccountId
    AND prev.AuditDate < cur.AuditDate
GROUP BY AccountId, cur.AuditDate

然后使用它：

WITH Ordering AS (
    SELECT AccountId, cur.AuditDate AS cur_AuditDate, MAX(prev.AuditDate) AS prev_AuditDate
    FROM AuditMyTable AS cur
    LEFT JOIN AuditMyTable AS prev
        ON prev.AccountId = cur.AccountId
        AND prev.AuditDate < cur.AuditDate
    GROUP BY AccountId, cur.AuditDate
)
SELECT cur.AccountId, cur.Amount as [NullAmount], prev.Amount as [PreviousNotNullAmount]
FROM AuditMyTable AS cur
INNER JOIN Ordering
    ON Ordering.AccountId = cur.AccountId
    AND Ordering.cur_AuditDate = cur.Audit_Date
LEFT JOIN AuditMyTable AS prev
    ON prev.AccountId = cur.AccountId
    AND prev.Audit_Date = Ordering.prev_AuditDate
于 2011-01-14T17:28:16.427 回答