Query with group by and max value

Question

Hi,
I have a table with many values of VAR_TRIMESTRALE for each COD_ISIN so I would take only the rows, for each COD_ISIN, that have the maximum of VAR_TRIMESTRALE.
select *
from spr_isin_drm_to b
group by b.COD_ISIN
having max(b.VAR_TRIMESTRALE)
I have tried to write the query in this way but it's wrong.
How can I write the correct query?
Thanks, bye bye.

Answer 1

Hi,
This is an example of a "Top-N" query:
SELECT   *       -- or list, if you don't want to see r_num
FROM    (
        SELECT  b.*
        ,       RANK () OVER
                    ( PARTITION BY  cod_isin
                      ORDER BY    var_trimestrale   DESC
                    )  AS r_num
        FROM    spr_isin_drm_to    b
WHERE   r_num = 1
;