查找最近的记录答案

【问题标题】：Find most recent record查找最近的记录
【发布时间】：2022-01-09 08:23:14
【问题描述】：

我有一个像这样的数据集：

org_id  patient_id  date
313     455259      2018-01-07
313     455259      2018-04-09
679     455259      2018-07-08
780     455259      2018-09-06

该患者在前两项索赔中属于同一组织。在那之后，他们改变了组织。我如何找到他们更改为的第一个组织？例如，这是我正在寻找的输出 -

org     patient     new_org
313     455259      679

【问题讨论】：

标签： sql postgresql window-functions

【解决方案1】：

我的意思是下面的查询可以帮助你：

with data as (
  -- get records with previous value of org_id
  select 
    patient_id,
    org_id,
    date,
    lag(org_id) over (partition by patient_id order by date) prev_org_id    
  from tbl
) 
-- select records where org_id changed
select * from data
where org_id != prev_org_id and prev_org_id is not null;

PostgreSQL window functions fiddle

【讨论】：

【解决方案2】：

此解决方案适用于多名患者。

With A As (
Select patient_id, org_id, 
       Lead(org_id) Over (Partition by patient_id Order by date, org_id) As new_org,
       Row_Number() Over (Partition by patient_id Order by date, org_id) As sort
From Tbl
),
B As (
Select patient_id, org_id, new_org,
       Row_Number() Over (Partition by patient_id Order by sort) As num
From A
Where org_id<>new_org
)
Select patient_id, org_id, new_org
From B
Where num=1

输出：

patient_id | org_id | new_org
___________|________|_________
   455259  |   313  |   679

【讨论】：

【解决方案3】：

这应该适用于所有边缘情况。

WITH data AS (
SELECT *, 
       LAG(org_id, 1, org_id) OVER (PARTITION BY patient_id ORDER BY date) AS prev_org,
       (org_id <> LAG(org_id, 1, org_id) OVER (PARTITION BY patient_id ORDER BY date)) :: int AS flag
FROM tb1
),
agg_data AS (
SELECT *, 
       MIN(CASE flag WHEN 1 THEN date END) OVER (PARTITION BY patient_id) AS min_date
FROM data
)
SELECT prev_org AS org, patient_id AS patient, org_id AS new_org
FROM agg_data
WHERE date = min_date;

见Demo

【讨论】：