SQL甲骨文發現相同的數據，並採取最新的一個

Question

我有一個SQL這給了我下面的輸出：

 column1 column2 column3 column4  column5 column6 column7 column8 column9 

#1 blabla blabla 15.10.2012 30.11.2014 7224 blabla blabla blabla blabla 
#2 blabla blabla 14.20.2011 30.11.2013 7224 blabla blabla blabla blabla 

column3和column4是DATE。

我的SQL：

select column1, column2, column3, column4, column5, 
(SELECT ov_merkmalwertid FROM V_OV_MERKMALWERT WHERE objektfk = table2.OV_OBJEKTID AND MERKMAL = 'censored1') column6, 
(SELECT ov_merkmalwertid FROM V_OV_MERKMALWERT WHERE objektfk = table2.OV_OBJEKTID AND MERKMAL = 'censored2') column7, 
(SELECT ov_merkmalwertid FROM V_OV_MERKMALWERT WHERE objektfk = table2.OV_OBJEKTID AND MERKMAL = 'censored3') column8, 
(SELECT ov_merkmalwertid FROM V_OV_MERKMALWERT WHERE objektfk = table2.OV_OBJEKTID AND MERKMAL = 'censored4') column9 
from 
table1, 
table2 
where 
table1.DEVICEID = table2.OV_OBJEKTID; 

正如你可以看到日期#1 column4比#2 column4 「更新」。

我需要一個SQL給我輸出，但檢查column5中的數字是否相同。如果它們是相同的，它只是向我顯示在column4中具有最新DATE的數據。

最終的結果應該沒有顯示#2

Answer 1

您可以使用ROW_NUMBER每column5最近column4日期以獲得記錄：

SELECT * 
FROM (
select ROW_NUMBER() OVER (PARTITION BY column5 ORDER BY column4 DESC) AS rn, 
     column1, column2, column3, column4, column5, ... etc 
FROM table1 
INNER JOIN table2 ON table1.DEVICEID = table2.OV_OBJEKTID) t 
WHERE t.rn = 1; 

你也應該使用ANSI標準JOIN語法，就像在上面的查詢中一樣。通過column5的column4和組

Answer 2

選擇MAX：

SELECT column1, column2, column3, MAX(column4), column5, 
     (SELECT ov_merkmalwertid 
      FROM V_OV_MERKMALWERT 
     WHERE objektfk = table2.OV_OBJEKTID 
      AND MERKMAL = 'censored1') column6, 
     (SELECT ov_merkmalwertid 
      FROM V_OV_MERKMALWERT 
     WHERE objektfk = table2.OV_OBJEKTID 
      AND MERKMAL = 'censored2') column7, 
     (SELECT ov_merkmalwertid 
      FROM V_OV_MERKMALWERT 
     WHERE objektfk = table2.OV_OBJEKTID 
      AND MERKMAL = 'censored3') column8, 
     (SELECT ov_merkmalwertid 
      FROM V_OV_MERKMALWERT 
     WHERE objektfk = table2.OV_OBJEKTID 
      AND MERKMAL = 'censored4') column9 
    FROM table1, 
     table2 
WHERE table1.DEVICEID = table2.OV_OBJEKTID 
GROUP BY column5;