Primi record di ogni gruppo univoco

[riccardo1975]

Correggimi se sbaglio perchè mi da 0 record sia la left join che la right join

left:

SELECT
a.identificativo AS A_IDENTIFICATIVO,
c.identificativo C_IDENTIFICATIVO
FROM (
select t1.data , t1.identificativo, t2.altro1, t2.altro2
from
(select identificativo, max(data) as data from tabella group by identificativo) t1
left join tabella t2
on t1.identificativo = t2.identificativo
and t1.data = t2.data
order by t1.data desc, t1.identificativo
) AS a
LEFT JOIN (
SELECT distinct(identificativo) FROM tabella
) AS c
ON a.identificativo = c.identificativo
WHERE c.identificativo IS NULL;

RIGHT:

SELECT
a.identificativo AS A_IDENTIFICATIVO,
c.identificativo C_IDENTIFICATIVO
FROM (
select t1.data , t1.identificativo, t2.altro1, t2.altro2
from
(select identificativo, max(data) as data from tabella group by identificativo) t1
left join tabella t2
on t1.identificativo = t2.identificativo
and t1.data = t2.data
order by t1.data desc, t1.identificativo
) AS a
RIGHT JOIN (
SELECT distinct(identificativo) FROM tabella
) AS c
ON a.identificativo = c.identificativo
WHERE a.identificativo IS NULL;