sql - 仅将一条重复记录的列值设置为 0？

Question

我有下表，并且我想将已删除列的值设置为零，仅针对具有重复名称的记录之一。

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

所以输出将是：

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-Server(>= 2005)，您可以使用CTEwith 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

演示

Answer 2

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

Answer 3

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