更新最新的紀錄 - SQL

Question

下面是我的數據

Key   Value  Date   STATUS 
001   AAA   2010-01-01  E 
001   BBB   2010-02-01  E 
001   CCC   2010-03-01  E 
002   XXX   2010-04-01  E 
002   YYY   2010-05-01  E 
002   ZZZ   2010-06-01  E 
003   HHH   2010-03-01  E 
003   GGG   2010-04-01  E 

我想更新與狀態C（電流）定鍵的最新的記錄。

這怎麼能用Update Statement來實現。

感謝

Answer 1

https://data.stackexchange.com/stackoverflow/query/8495/so3358976

-- SO3358976 
-- update-lastest-record-for-each-key-sql 

CREATE TABLE #temp ([Key] char(3) NOT NULL 
, [Value] char(3) NOT NULL 
, [Date] date NOT NULL 
, [Status] char(1) NOT NULL) 

INSERT INTO #temp VALUES ('001', 'AAA', '2010-01-01', 'E') 
,('001', 'BBB', '2010-02-01', 'E') 
,('001', 'CCC', '2010-03-01', 'E') 
,('002', 'XXX', '2010-04-01', 'E') 
,('002', 'YYY', '2010-05-01', 'E') 
,('002', 'ZZZ', '2010-06-01', 'E') 
,('003', 'HHH', '2010-03-01', 'E') 
,('003', 'GGG', '2010-04-01', 'E') 

;WITH Latest AS (
    SELECT [Key], MAX([Date]) AS LastDate FROM #temp GROUP BY [Key] 
) 
UPDATE t 
SET [Status] = 'C' 
FROM #temp AS t 
INNER JOIN Latest 
    ON t.[Key] = Latest.[Key] 
    AND t.[Date] = Latest.[LastDate]​​​​​​​​​​ 

​SELECT * FROM #temp​ 

Answer 2

update table_name set status = 'C' where date = max(date); 

Answer 3

我得到了這個工作作爲

WITH DISTKEYS (KEYS) 
AS (SELECT DISTINCT [KEY] FROM dbo.myTable) 
UPDATE TargetTable 
SET [status] = 'C' 
FROM dbo.myTable AS TargetTable JOIN DISTKEYS ds ON TargetTable.[key] = ds.[keys] 
WHERE [date] = (SELECT MAX([date]) FROM dbo.myTable WHERE [key] = ds.[keys]) 

感謝