sql - 如何从基于多个表的 Oracle 结果集中删除重复项

Question

我有 2 个表:一个保存核心数据的主 APPLICATION 表，以及一个反射(reflect) APPLICATION 表中核心数据状态变化的 STATUSTRACKING 表。

APPLICATION表和STATUSTRACKING表之间是1:N的关系。示例如下:

-- APPLICATION
SELECT A.ID, A.DECISIONON, A.APPLICATIONSTATUS_ID AS CURRENTSTATUS
FROM APPLICATION A
WHERE A.ID=1099;

Results:
ID      DECISIONON  CURRENTSTATUS
1099    5/05/2009   5

-- STATUS TRACKING
SELECT ST.ID, ST.APPLICATION_ID AS APP_ID, ST.APPLICATIONSTATUS_ID AS STATUS, ST.CREATEDATE 
FROM STATUSTRACKING ST
WHERE ST.APPLICATION_ID=1099
ORDER BY ST.CREATEDATE DESC;

Results:
ID      APP_ID  STATUS  CREATEDATE
44466   1099    5       5/05/2009
44458   1099    7       5/05/2009
10826   1099    8       21/07/2008
9770    1099    7       9/07/2008
4410    1099    3       9/05/2008
3814    1099    2       2/05/2008
3803    1099    1       2/05/2008

问题: 我需要为特定状态选择具有最近日期的 STATUSTRACKING 记录。这是我的尝试:

SELECT A.ID AS APP_ID, A.APPLICATIONSTATUS_ID AS CURR_ST, Z.ID AS ST_ID, Z.CREATEDATE, Z.APPLICATIONSTATUS_ID AS OLD_ST
FROM APPLICATION A, STATUSTRACKING Z
WHERE A.APPLICATIONSTATUS_ID in (5,6)
    AND A.ID IN (337,1099,1404,9441)
    AND Z.APPLICATIONSTATUS_ID = 7
    AND Z.APPLICATION_ID=A.ID
ORDER BY A.ID ASC, Z.CREATEDATE DESC;

Results:
APP_ID  CURR_ST ST_ID       CREATEDATE  OLD_ST
337     6       13978       17/08/2008  7
1099    5       44458       5/05/2009   7
1099    5       9770        9/07/2008   7
1404    6       15550       28/08/2008  7
9441    5       49271       3/06/2009   7
9441    5       46058       13/05/2009  7

问题是重复的行。我必须只显示具有最新 CreateDate 的行。在 App_ID 1099 的情况下，它将是这条记录:

1099    5       44458       5/05/2009   7

我显然不想排除不重复的行。

我认为我在这条语句的正确轨道上给出了我正在寻找的行:

SELECT A.ID, A.APPLICATION_ID, A.APPLICATIONSTATUS_ID, A.CREATEDATE
FROM    (SELECT * 
            FROM STATUSTRACKING 
            WHERE APPLICATIONSTATUS_ID=7 
                AND APPLICATION_ID=1099 
            ORDER BY CREATEDATE DESC) A
WHERE ROWNUM = 1;

...但我似乎无法让它与我的主要选择语句一起使用。

我想要的结果集应该是这样的:

APP_ID  CURR_ST ST_ID       CREATEDATE  OLD_ST
337     6       13978       17/08/2008  7
1099    5       44458       5/05/2009   7
1404    6       15550       28/08/2008  7
9441    5       49271       3/06/2009   7
etc. ...

我不是 Oracle/SQL 专家，因此我们将不胜感激。

Answer 1

最简单的方法可能是使用解析函数。有点像

SELECT *
  FROM (
    SELECT A.ID AS APP_ID, 
           A.APPLICATIONSTATUS_ID AS CURR_ST, 
           Z.ID AS ST_ID, 
           Z.CREATEDATE, 
           Z.APPLICATIONSTATUS_ID AS OLD_ST,
           rank() over (partition by a.id order by z.createDate desc) rnk
      FROM APPLICATION A, 
           STATUSTRACKING Z
     WHERE A.APPLICATIONSTATUS_ID in (5,6)
       AND A.ID IN (337,1099,1404,9441)
       AND Z.APPLICATIONSTATUS_ID = 7
       AND Z.APPLICATION_ID=A.ID
    )
 WHERE rnk = 1

如果可能有关系，您可能希望使用 ROW_NUMBER 或 DENSE_RANK 分析函数而不是 RANK。