如何将select转换为update语句

Question

我有一个select语句，我需要将它转换为Update语句。

SELECT GUID,seq original_seq_no, ROW_NUMBER() 
OVER (PARTITION BY GUID ORDER BY seq) AS new_seq_no 
FROM CHK_SEQ; 

究竟上面的查询所做的就是，假设我有一个多条记录与唯一的GUID和列SEQ值是表CHK_SEQ 6,9,10。然后运行上述查询将SEQ的值更改为1,2,3，即new_seq_no。

任何人都可以请帮助我这个。

谢谢。

Answer 1

试试这个（SQL-Server 2005和以上）：

With cte as (
    Select GUID,seq, row_number() over (partition by GUID order by seq) AS new_seq_no 
    From CHK_SEQ 
) 
Update c 
Set c.seq = new_seq_no 
From CHK_SEQ c 
    Join cte on c.Guid = cte.Guid and c.seq = cte.seq; 

Answer 2

试试这个，

with cte 
AS 
(
SELECT GUID,seq original_seq_no, ROW_NUMBER() 
OVER (PARTITION BY GUID ORDER BY seq) AS new_seq_no 
FROM CHK_SEQ 
) 

update CHK_SEQ 
set  CHK_SEQ.seq = r.new_seq_no 
from cte r 
where CHK_SEQ.seq = r.original_seq_no AND CHK_SEQ.GUID= r.GUID; 

Answer 3

merge into CHK_SEQ 
using 
    SELECT rowid as rid, 
      ROW_NUMBER() OVER (PARTITION BY GUID ORDER BY seq) AS new_seq_no 
    FROM CHK_SEQ 
) t on (chk_seq.rowid = t.rid) 
when matched then update 
    set seq = new_seq_no;