Question

说我有两张桌子(SQL Fiddle)。在不同时间戳记录值的一个，另一个表示对最近值进行采样的ID和日期时间。使用类似于Kevin Meade NEAREST NEIGHBOR PREFERENCE LOW的东西（但在SQL Server 2008中），我想找到最接近目标（人口普查）日期的指示ID的（非空值），但不是（人口普查）日期。如果存在与人口普查日期匹配的行，请使用该行（除非它具有空值）。如果在人口普查日期之前没有任何行，那么找到最接近人口普查日期而不是人口普查日期的行并使用该行。

第一张表：

CREATE TABLE Recorded_Vent_Types
    ([PAT_ENC_CSN_ID] int, [RECORDED_TIME] datetime, [MEAS_VALUE] varchar(9));

INSERT INTO Recorded_Vent_Types
    ([PAT_ENC_CSN_ID], [RECORDED_TIME], [MEAS_VALUE])
VALUES
    (11117777,  '2013-06-08 19:36:00.000',  'SIMV/PRVC'),
    (11117777,  '2013-06-08 22:21:00.000',  'PRVC/AC'),
    (11117777,  '2013-06-09 00:10:00.000',  NULL),
    (11117777,  '2013-06-09 03:00:00.000',  'SIMV/PRVC'),
    (11117777,  '2013-06-09 23:59:00.000',  'SIMV/PRVC'),
    (11117777,  '2013-06-10 00:00:00.000',  'NAVA'),
    (11117777,  '2013-06-10 00:20:00.000',  'PS'),
    (11117777,  '2013-06-10 00:25:00.000',  NULL),
    (555999,    '2013-06-08 00:36:00.000',  NULL),
    (555999,    '2013-06-08 22:21:00.000',  'PRVC/AC'),
    (555999,    '2013-06-09 00:10:00.000',  'SIMV/PRVC'),
    (555999,    '2013-06-11 23:15:00.000',  'BIVENT'),
    (555999,    '2013-06-12 00:00:00.000',  NULL),
    (555999,    '2013-06-12 00:20:00.000',  'PS');

第二张表：

CREATE TABLE Census
    ([PAT_ENC_CSN_ID] int, [CENSUS_TIME] datetime);

INSERT INTO Census
    ([PAT_ENC_CSN_ID], [CENSUS_TIME])
VALUES
    (11117777, '2013-06-08 00:00:00'),
    (11117777, '2013-06-09 00:00:00'),
    (11117777, '2013-06-10 00:00:00'),
    (11117777, '2013-06-11 00:00:00'),
    (555999, '2013-06-08 00:00:00'),
    (555999, '2013-06-09 00:00:00'),
    (555999, '2013-06-11 00:00:00'),
    (555999, '2013-06-12 00:00:00');

这里是米德先生的Oracle代码，针对给定ID在一个表格中提供类似的内容：

select *
from claim_history
where claim_id = 1
and status_date =
   (
    select min(status_date)
    from (
          select max(status_date) status_date
          from claim_history
          where claim_id = 1
          and status_date <= sysdate-3
          union all
          select min(status_date)
          from claim_history
          where claim_id = 1
          and status_date > sysdate-3
         )
   )
/

我的所需结果集：

PAT_ENC_CSN_ID    CENSUS_TIME           RECORDED_TIME               MEAS_VALUE
555999      June, 08 2013 00:00:00+0000 June, 08 2013 22:21:00+0000 PRVC/AC
555999      June, 09 2013 00:00:00+0000 June, 08 2013 22:21:00+0000 PRVC/AC
555999      June, 11 2013 00:00:00+0000 June, 09 2013 00:10:00+0000 SIMV/PRVC
555999      June, 12 2013 00:00:00+0000 June, 11 2013 23:15:00+0000 BIVENT
11117777    June, 08 2013 00:00:00+0000 June, 08 2013 19:36:00+0000 SIMV/PRVC
11117777    June, 09 2013 00:00:00+0000 June, 08 2013 22:21:00+0000 PRVC/AC
11117777    June, 10 2013 00:00:00+0000 June, 10 2013 00:00:00+0000 NAVA
11117777    June, 11 2013 00:00:00+0000 June, 10 2013 00:20:00+0000 PS

@Gordon Linoff给了我一个想法，即在人口普查时间和记录时间之间使用日期差异的绝对值。这导致我修改@bobs解决方案here。

SELECT * FROM
    (
    SELECT rvt.PAT_ENC_CSN_ID, CENSUS_TIME, RECORDED_TIME, MEAS_VALUE, ABS(DATEDIFF(s, c.CENSUS_TIME, RECORDED_TIME)) diff,
        ROW_NUMBER() OVER (PARTITION BY rvt.PAT_ENC_CSN_ID, c.CENSUS_TIME ORDER BY ABS(DATEDIFF(s, c.CENSUS_TIME, RECORDED_TIME))) AS SEQUENCE
    FROM Recorded_Vent_Types rvt join Census c on rvt.PAT_ENC_CSN_ID=c.PAT_ENC_CSN_ID
    WHERE MEAS_VALUE IS NOT NULL
    ) as m
WHERE SEQUENCE = 1
ORDER BY PAT_ENC_CSN_ID,CENSUS_TIME
;

但这会返回（绝对）最接近的记录时间，而不会优先考虑普查时间之前的记录时间。结果：

PAT_ENC_CSN_ID    CENSUS_TIME           RECORDED_TIME               MEAS_VALUE
555999      June, 08 2013 00:00:00+0000 June, 08 2013 22:21:00+0000 PRVC/AC
555999      June, 09 2013 00:00:00+0000 June, 09 2013 00:10:00+0000 SIMV/PRVC
555999      June, 11 2013 00:00:00+0000 June, 11 2013 23:15:00+0000 BIVENT
555999      June, 12 2013 00:00:00+0000 June, 12 2013 00:20:00+0000 PS
11117777    June, 08 2013 00:00:00+0000 June, 08 2013 19:36:00+0000 SIMV/PRVC
11117777    June, 09 2013 00:00:00+0000 June, 08 2013 22:21:00+0000 PRVC/AC
11117777    June, 10 2013 00:00:00+0000 June, 10 2013 00:00:00+0000 NAVA
11117777    June, 11 2013 00:00:00+0000 June, 10 2013 00:20:00+0000 PS

Answer 1

您可以在Oracle和SQL Server中以相关子查询的形式执行此操作，因为除了前1个，这几乎是标准SQL。

以下是查询：

select *,
       (select top 1 PAT_ENC_CSN_ID
        from census c
        where c.census_time <= rvt.recorded_time
        order by (case when c.census_time <= rvt.recorded_time then 1 else 0
                  end) desc,
                 (case when c.census_time <= rvt.recorded_time then c.census_time
                  end) desc,
                 c.census_time asc
       ) as nearestVal
from Recorded_Vent_Types rvt

子查询根据order by返回一行，这是查询的关键。它有三个部分。

第一次将所有人口普查时间放在开始时记录的时间之前。第二个按人口普查时间降序对这些进行排序，第三个按升序时间对其余部分进行排序。我想用以下内容替换最后两个：

abs(c.census_time - rvt.recorded_time)

因为这在逻辑上是它的作用。唉，这不起作用，因为abs()不适用于datetime。然后我必须使用datediff()函数或case语句，它看起来会变得更复杂。

时间点的最近邻

1 个答案: