更新許多行 - 每組一行

Question

我想弄明白這一點。我有一張有幾十萬行的桌子。每個作業＃大約有8行。我需要根據另一列的最高值爲每個作業＃更新一列。其中oper_num是最大

作業的cntrl_point需要設置爲1。

UPDATE jobroute 
SET cntrl_point = 1 
SELECT DISTINCT job, cntrl_point, MAX(oper_num) OVER (PARTITION BY job) MAX_Oper_Num 
FROM jobroute 
WHERE job not like 'J%' AND suffix = 0 

我假設我用錯了OVER PARTITION。我想也許CURSOR會更合適，但我不知道該怎麼做。

任何幫助將不勝感激。

Answer 1

在SQL Server中，你可以使用這個row_number()：

with toupdate as (
     select jr.*, row_number() over (partition by job order by oper_num desc) as seqnum 
     from jobroute jr 
     where job not like 'J%' AND suffix = 0 
    ) 
UPDATE toupdate 
    SET cntrl_point = 1 
    WHERE seqnum = 1;