在不按1行SQL查询分组的情况下获取最大值

Question

i need help to get a value from a table without grouping one field.

the table design is like this

Progress    DocNum    Project
---------------------------
30        10         1111
70        11         1111
30        10         1112
100       12         1111
70        13         1112

then i want data like this. get the max progress for each project, without grouping DocNum

Progress    DocNum    Project
---------------------------
100       12         1111
70        13         1112

how someone can help me. thankyou very much before

Answer 1

You can use window functions row_number to get one row with max progress per project:

Select *
From (
  Select t.*,
    Row_number() over (partition by project order by progress desc) rn
  From your_table t
) t where rn = 1

If there are multiple rows with max progress per project and you want to retrieve all of them, use rank instead:

Select *
From (
  Select t.*,
    Rank() over (partition by project order by progress desc) rnk
  From your_table t
) t where rnk = 1

Note:

Both the above queries read the table only once. The accepted solution reads the table twice.

Answer 2

You could use this

SELECT t.progress, t.docnum, t.project
FROM table_name t
INNER JOIN (
    SELECT MAX(progress) max_progress,
        project
    FROM table_name
    GROUP BY project
) mt
ON t.project = mt.project
    AND t.progress = mt.progress;

Or this

SELECT progress, docnum, project
FROM table_name 
WHERE (progress, project) IN (
        SELECT MAX(progress) max_progress,
            project
        FROM table_name
        GROUP BY project
    );