SQL从多行返回MAX值

Question

I have tried many solutions and nothing seems to work. I am trying to return the MAX status date for a project. If that project has multiple items on the same date, then I need to return the MAX ID. So far I have tried this:

    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

It returns the following:

I am getting multiple records for PRJSTAT_PRJA_ID, but I only want to return the row with the MAX PRJSTAT_ID. Any thoughts?

Answer 1

Take out the MAX on the ID on the subquery:

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

Or remove the need to join:

  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

Your problem is ties. You want the record with the maximum date per PRJSTAT_PRJA_ID and in case of a tie the record with the highest ID. The easiest way to rank records per group and only keep the best record is 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;