Classement conditionnel Oracle SQL

Si je comprends bien, vous pouvez essayer d'utiliser CASE WHEN avec sum fonction de fenêtre

CASE WHEN vérifier col3 n'est pas null cumuler sinon afficher NULL

CREATE TABLE T(
  col1 VARCHAR(5),
  col2 DATE,
  col3 DATE
);

INSERT INTO T VALUES ( 'a' , to_date('2018-01-20','YYYY-MM-DD') , to_date('2018-03-04','YYYY-MM-DD'));  
INSERT INTO T VALUES ( 'a' , to_date('2018-01-24','YYYY-MM-DD') , to_date('2018-04-04','YYYY-MM-DD'));  
INSERT INTO T VALUES ( 'b' , to_date('2018-01-02','YYYY-MM-DD') , to_date('2018-05-03','YYYY-MM-DD'));  
INSERT INTO T VALUES ( 'c' , to_date('2017-01-02','YYYY-MM-DD') , to_date('2017-05-08','YYYY-MM-DD'));  
INSERT INTO T VALUES ( 'd' , TO_DATE('2016-05-24','YYYY-MM-DD') , null);  
INSERT INTO T VALUES ( 'c' , TO_DATE('2018-02-05','YYYY-MM-DD') , to_date('2018-05-03','YYYY-MM-DD'));  
INSERT INTO T VALUES ( 'c' , TO_DATE('2018-07-28','YYYY-MM-DD') , null);  

Requête 1 :

select t1.*,
    rank() OVER(partition by col1 order by col2 desc) rank1,
    (CASE WHEN COL3 IS NOT NULL THEN
       SUM(CASE WHEN COL3 IS NOT NULL THEN 1 ELSE 0 END) OVER(partition by col1 order by col2 desc)
    ELSE
       NULL
    END) rank2
FROM T t1

Résultats :

| COL1 |                 COL2 |                 COL3 | RANK1 |  RANK2 |
|------|----------------------|----------------------|-------|--------|
|    a | 2018-01-24T00:00:00Z | 2018-04-04T00:00:00Z |     1 |      1 |
|    a | 2018-01-20T00:00:00Z | 2018-03-04T00:00:00Z |     2 |      2 |
|    b | 2018-01-02T00:00:00Z | 2018-05-03T00:00:00Z |     1 |      1 |
|    c | 2018-07-28T00:00:00Z |               (null) |     1 | (null) |
|    c | 2018-02-05T00:00:00Z | 2018-05-03T00:00:00Z |     2 |      1 |
|    c | 2017-01-02T00:00:00Z | 2017-05-08T00:00:00Z |     3 |      2 |
|    d | 2016-05-24T00:00:00Z |               (null) |     1 | (null) |