SQL甲骨文发现相同的数据，并采取最新的一个

Question

我有一个SQL这给了我下面的输出：

 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”。

我需要一个SQL给我输出，但检查column5中的数字是否相同。如果它们是相同的，它只是向我显示在column4中具有最新DATE的数据。

最终的结果应该没有显示#2

Answer 1

您可以使用ROW_NUMBER每column5最近column4日期以获得记录：

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; 

你也应该使用ANSI标准JOIN语法，就像在上面的查询中一样。通过column5的column4和组

Answer 2

选择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;