Question

我正在尝试重新排序数据库中的某些记录。我想出了这个剧本：

UPDATE r
SET r.DisplaySequence = temp.DisplaySequence
FROM    
    SomeTable r JOIN
    (
        SELECT RecordID, ROW_NUMBER() OVER (ORDER BY DisplaySequence, InsertedOn) AS DisplaySequence
        FROM dbo.SomeTable WHERE FacCode IS NULL AND UserID IS NULL
    ) AS temp ON temp.RecordID = r.RecordID 
WHERE FacCode IS NULL AND UserID IS NULL

这将使用新值更新DisplaySequence列，并尊重当前记录可能包含的任何订单。

但是，每当DisplaySequence更改时，我都需要“重置”RecordCategoryID。

所以，如果我有这些数据：

RecordID | RecordCategoryID | DisplaySequence
---------------------------------------------
   1            1                  1
   2            1                  2
   3            1                  3
   4            2                  4
   5            2                  5
   6            2                  6

由于DisplaySequence已更改，RecordCategoryID应该从最后3条记录的1重新开始，但我无法弄清楚如何“重置”ROW_NUMBER()值？

Answer 1

詹姆斯Z在评论中回答：

使用 row_number()

的partition by条款的over()部分

UPDATE r
SET r.DisplaySequence = temp.DisplaySequence
FROM SomeTable r 
  JOIN (
        SELECT RecordID
        , row_number() over (
          partition by RecordCategoryId
          order BY DisplaySequence, InsertedOn
          ) AS DisplaySequence
        FROM dbo.SomeTable 
        WHERE FacCode IS NULL 
          AND UserID IS NULL
    ) AS temp ON temp.RecordID = r.RecordID 
WHERE FacCode IS NULL 
  AND UserID IS NULL

如何在特定列更改时重置值？

1 个答案: