SQL查询来更新行

Question

在表

我有数据在以下格式

ID DocNumber RevOrder 
1 DOC-001  NULL 
2 DOC-001  NULL 
3 DOC-001  NULL 
4 DOC-002  NULL 
5 D0C-002  NULL 
6 D0C-003  NULL 

我需要在更新RevOrder列格式如下

ID DocNumber RevOrder 
1 DOC-001  3 
2 DOC-001  2 
3 DOC-001  1 
4 DOC-002  2 
5 D0C-002  1 
6 D0C-003  1 

逻辑是：DocNumber可被复制和带有最大ID的DocNumber获得RevOrder = 1，然后获取RevOrder = 2等等......我如何实现上述场景？

Answer 1

使用基于一个ROW_NUMBER()在分区此UPDATE声明：

;WITH UpdateData AS 
(
    SELECT 
     ID, DocNumber, 
     ROW_NUMBER() OVER(PARTITION BY DocNumber ORDER BY ID DESC) AS 'RowNum' 
    FROM dbo.YourTable 
) 
UPDATE dbo.YourTable 
SET RevOrder = RowNum 
FROM dbo.YourTable t 
INNER JOIN UpdateData ud ON t.ID = ud.ID 

Answer 2

从SQL Server 2005及以上版本，你可以使用

RANK() OVER (PARTITION BY DocNumber ORDER BY ID ASC) AS RevOrder 

Answer 3

使用ROW_NUMBER() & PARTITION BY

SELECT ID, 
     DocNumber, 
     ROW_NUMBER() OVER(PARTITION BY DocNumber ORDER BY DocNumber DESC) AS RevOrder 
FROM @TestTable 

您可以查看/测试在这里工作的例子：http://data.stackexchange.com/stackoverflow/q/116435/

Answer 4

我想具有分区by子句的row_number（）函数将工作

declare @temp as table(
ID int not null 
,Doc_Num varchar(20) not null 
,RevOrder int null 
) 
insert into @temp 
values 
(1,'DOC-001',null) 
,(2,'DOC-001',null) 
,(3,'DOC-001',null) 
,(4,'DOC-002',null) 
,(5,'DOC-002',null) 
,(6,'DOC-003',null) 


select * from @temp 


select 
t.ID 
,t.Doc_Num 
,ROW_NUMBER() over(partition by t.Doc_num order by t.ID desc) 
from 
@temp t 
order by t.ID