如果可以在同一日期找到多个记录，如何选择一个值

Question

有人可以建议我改进此子查询，使其仅能基于以下计算获得单个记录，本文下面的子查询带来以下结果：

PERCENT ¦ LOG_DATE ¦ APP ¦ REQ_ID
55 ¦ 2017-02-07 15:44:22 ¦ HUO ¦ 253333
63 ¦ 2017-02-08 10:42:18 ¦ CQS ¦ 265265
75 ¦ 2017-02-08 06:55:12 ¦ CQS ¦ 265265
84 ¦ 2017-02-09 08:35:42 ¦ CQS ¦ 265265
40 ¦ 2017-02-09 09:45:14 ¦ PLK ¦ 277777

我只想查看结果中的那些记录，这些记录每个日期都有最新的日期（al.AU_TIME）。 目标是努力处理百分比值为“ 63”的记录。 查询应带来：

55 ¦ 2017-02-07 15:44:22 ¦ HUO ¦ 253333
63 ¦ 2017-02-08 10:42:18 ¦ CQS ¦ 265265
84 ¦ 2017-02-09 08:35:42 ¦ CQS ¦ 265265
40 ¦ 2017-02-09 09:45:14 ¦ PLK ¦ 277777

因此，如果同一天有多个具有相同REQ_ID的记录，该怎么办。

SELECT TO_NUMBER(RTRIM(ap.AP_NEW_VALUE,'%')) as PERCENT,
   al.AU_TIME as LOG_DATE,
   req.RQ_USER_03 as APP,
   req.RQ_REQ_ID as REQ_ID
FROM AUDIT_PROPERTIES ap,
     AUDIT_LOG al,
     REQ
WHERE al.AU_ACTION_ID = ap.AP_ACTION_ID and
      req.RQ_REQ_ID = al.AU_ENTITY_ID and
      req.rq_req_date BETWEEN TO_DATE('05/02/2017','dd/mm/yyyy') AND TO_DATE('20/02/2017','dd/mm/yyyy') and
      ap.AP_FIELD_NAME = 'RQ_USER_58'

提前致谢。

Answer 1

一种典型的做法是使用row_number() 。 据您所知，最好的是：

select a.*
from (select a.*,
             row_number() over (partition by req_id order by log_date desc) as seqnum
      from atable a
     ) a
where seqnum = 1;

Answer 2

您可以通过编写内部查询或创建一个中间表来做到这一点，该中间表仅按日期对数据进行分组并计算每个日期的max_time。内部查询如下所示：

SELECT cast(al.AU_TIME as date) as LOG_DATE,
max(al.AU_TIME) as max_LOG_TIME
FROM AUDIT_PROPERTIES ap,
     AUDIT_LOG al,
     REQ
WHERE al.AU_ACTION_ID = ap.AP_ACTION_ID and
      req.RQ_REQ_ID = al.AU_ENTITY_ID and
      req.rq_req_date BETWEEN TO_DATE('05/02/2017','dd/mm/yyyy') AND TO_DATE('20/02/2017','dd/mm/yyyy') and
      ap.AP_FIELD_NAME = 'RQ_USER_58'
GROUP BY LOG_DATE

然后需要将外部查询与此内部查询的时间戳值结合起来，以获取那些记录

Select TO_NUMBER(RTRIM(ap.AP_NEW_VALUE,'%')) as PERCENT,
        al.AU_TIME,
        req.RQ_USER_03 as APP,
   req.RQ_REQ_ID as REQ_ID
   FROM AUDIT_PROPERTIES ap
   inner join (
SELECT cast(al.AU_TIME as date) as LOG_DATE,
max(al.AU_TIME) as max_LOG_TIME
FROM AUDIT_PROPERTIES ap,
     AUDIT_LOG al,
     REQ
WHERE al.AU_ACTION_ID = ap.AP_ACTION_ID and
      req.RQ_REQ_ID = al.AU_ENTITY_ID and
      req.rq_req_date BETWEEN TO_DATE('05/02/2017','dd/mm/yyyy') AND TO_DATE('20/02/2017','dd/mm/yyyy') and
      ap.AP_FIELD_NAME = 'RQ_USER_58'
GROUP BY LOG_DATE) 
AS X
ON ap.AU_TIME= X.max_LOG_TIME
INNER JOIN AUDIT_LOG al
on al.AU_ACTION_ID = ap.AP_ACTION_ID
INNER JOIN REQ
ON req.RQ_REQ_ID = al.AU_ENTITY_ID
WHERE req.rq_req_date BETWEEN TO_DATE('05/02/2017','dd/mm/yyyy') AND TO_DATE('20/02/2017','dd/mm/yyyy') and
      ap.AP_FIELD_NAME = 'RQ_USER_58'

Answer 3

这可以在单个聚合查询中完成（没有子查询）。 按req_id和trunc(log_date) ，然后每组仅选择一个记录。 req_id和max(log_date)各组内 ，也就是每天内）是显而易见的。 然后使用first/last函数（ keep (dense_rank...) 。如果对于给定的日期和时间，可能有两行具有完全相同的日期和时间 （倒数第二行），则只需小心一点。 req_id 。

这是一种方法。 我将您提供的测试数据放在WITH子句中，以用于测试和说明目的，但这不是查询的一部分。

with
     test_data ( percent, log_date, app, req_id ) as (
       select 55, to_date('2017-02-07 15:44:22', 'yyyy-mm-dd hh24:mi:ss'), 'HUO', 253333
       from dual union all
       select 63, to_date('2017-02-08 10:42:18', 'yyyy-mm-dd hh24:mi:ss'), 'CQS', 265265
       from dual union all
       select 75, to_date('2017-02-08 06:55:12', 'yyyy-mm-dd hh24:mi:ss'), 'CQS', 265265
       from dual union all
       select 84, to_date('2017-02-09 08:35:42', 'yyyy-mm-dd hh24:mi:ss'), 'CQS', 265265
       from dual union all
       select 40, to_date('2017-02-09 09:45:14', 'yyyy-mm-dd hh24:mi:ss'), 'PLK', 277777
       from dual
     )
--  End of test data (not part of the solution). SQL query begins BELOW THIS LINE
select max(percent) keep (dense_rank last order by log_date)          as percent,
       max(log_date)                                                  as log_date,
       max(app)     keep (dense_rank last order by log_date, percent) as app,
       req_id
from   test_data
group by req_id, trunc(log_date)
order by log_date, req_id
;

PERCENT LOG_DATE   APP  REQ_ID
------- ---------- --- -------
     55 2017-02-07 HUO  253333
     63 2017-02-08 CQS  265265
     84 2017-02-09 CQS  265265
     40 2017-02-09 PLK  277777

4 rows selected.