SQL从多行中返回最大值

Question

我尝试了很多解决方案，似乎没有任何工作。我正在尝试返回项目的MAX状态日期。如果该项目在同一天有多个项目，那么我需要返回MAX ID。到目前为止，我已经试过这样：

SELECT PRJSTAT_ID, PRJSTAT_PRJA_ID, PRJSTAT_STATUS, PRJSTAT_DATE 
From Project_Status 
JOIN 
(SELECT MAX(PRJSTAT_PRJA_ID) as MaxID, MAX(PRJSTAT_DATE) as MaxDate 
FROM Project_Status 
Group by PRJSTAT_PRJA_ID) 
On 
PRJSTAT_PRJA_ID = MaxID and PRJSTAT_DATE = MaxDate 
Order by PRJSTAT_PRJA_ID 

它返回如下：

我获得多个记录PRJSTAT_PRJA_ID，但我只希望与MAX PRJSTAT_ID返回的行。有什么想法吗？

Answer 1

取出MAX上的ID的子查询：

SELECT PRJSTAT_ID, PRJSTAT_PRJA_ID, PRJSTAT_STATUS, PRJSTAT_DATE 
From Project_Status 
JOIN 
(SELECT PRJSTAT_PRJA_ID as ID, MAX(PRJSTAT_DATE) as MaxDate 
FROM Project_Status 
Group by PRJSTAT_PRJA_ID) 
On 
PRJSTAT_PRJA_ID = ID and PRJSTAT_DATE = MaxDate 
Order by PRJSTAT_PRJA_ID 

Answer 2

或删除需要加入：

SELECT * FROM  
(SELECT PRJSTAT_ID, PRJSTAT_PRJA_ID, PRJSTAT_STATUS, PRJSTAT_DATE, 
ROW_NUMBER() OVER (PARTITION BY PRJSTAT_PRJA_ID ORDER BY PRJSTAT_DATE DESC) 
AS SEQ, 
ROW_NUMBER() OVER (PARTITION BY PRJSTAT_PRJA_ID ORDER BY PRJSTAT_PRJA_ID 
DESC) AS IDSEQ 
From Project_Status 
)PR 
WHERE SEQ = 1 
AND IDSEQ = 1 

Answer 3

你的问题是联系。您希望记录的最大日期为PRJSTAT_PRJA_ID，并且在与最高ID的记录匹配的情况下。排名每组记录只保留最佳战绩最简单的方法是ROW_NUMBER：

select prjstat_id, prjstat_prja_id, prjstat_status, prjstat_date 
from 
(
    select 
    project_status.*, 
    row_number() over (partition by prjstat_prja_id 
         order by prjstat_date desc, prjstat_id desc) as rn 
    from project_status 
) 
where rn = 1 
order by prjstat_prja_id;