僅爲其中一個重複記錄將列的值設置爲0？

Question

我有下表，並且我想將只有一個具有重複名稱的記錄的已刪除列的值設置爲零。

id  name  deleted 
------------------------ 
1  a   1 
2  a   1 
3  a   1 
4  b   1 
5  c   1 
6  d   1 

所以輸出將是：

id  name  deleted 
------------------------ 
1  a   0 
2  a   1 
3  a   1 
4  b   0 
5  c   0 
6  d   0 

Answer 1

如果您的DBMS是SQL-服務器（> = 2005），你可以使用一個CTE與ROW_NUMBER：

WITH CTE AS 
(
    SELECT ID, Name, Deleted, 
    RN = ROW_NUMBER() OVER(PARTITION BY name ORDER BY ID) 
    FROM dbo.T 
) 
UPDATE CTE 
SET Deleted = 0 
WHERE RN = 1 

DEMO

Answer 2

UPDATE A 
SET A.deleted = 0 
FROM Tbl A 
    LEFT JOIN Tbl B 
    ON A.Name = B.Name 
     AND A.Id > B.Id 
WHERE B.Id IS NULL 

Answer 3

UPDATE Tbl SET deleted = 0 WHERE id IN 
(SELECT MIN(id) FROM Tbl GROUP BY name)