Oracle SQL - DENSE_RANK

Question

I have a Client data table, selected columns of which are shown below:

Row_ID  Client_ID  Status_ID  From_date           To_date
  1     123456       4               


        

Answer 1

Here's a solution using Tabibitosan:

with client as (select 1 row_id, 123456 client_id, 4 status_id, to_date('20/12/2007 18:02','dd/mm/yyyy hh24:mi') from_date, to_date('20/12/2007 18:07','dd/mm/yyyy hh24:mi') todate from dual union all
                select 2 row_id, 789087 client_id, 4 status_id, to_date('20/12/2007 18:02','dd/mm/yyyy hh24:mi') from_date, to_date('20/12/2007 18:07','dd/mm/yyyy hh24:mi') todate from dual union all
                select 3 row_id, 789087 client_id, 4 status_id, to_date('20/12/2007 18:07','dd/mm/yyyy hh24:mi') from_date, to_date('20/12/2007 18:50','dd/mm/yyyy hh24:mi') todate from dual union all
                select 4 row_id, 789087 client_id, 4 status_id, to_date('20/12/2007 18:50','dd/mm/yyyy hh24:mi') from_date, to_date('21/12/2007 10:38','dd/mm/yyyy hh24:mi') todate from dual union all
                select 5 row_id, 123456 client_id, 4 status_id, to_date('20/12/2007 18:07','dd/mm/yyyy hh24:mi') from_date, to_date('20/12/2007 18:50','dd/mm/yyyy hh24:mi') todate from dual union all
                select 6 row_id, 123456 client_id, 4 status_id, to_date('20/12/2007 18:50','dd/mm/yyyy hh24:mi') from_date, to_date('21/12/2007 10:38','dd/mm/yyyy hh24:mi') todate from dual union all
                select 7 row_id, 123456 client_id, 4 status_id, to_date('21/12/2007 10:38','dd/mm/yyyy hh24:mi') from_date, to_date('21/12/2007 16:39','dd/mm/yyyy hh24:mi') todate from dual union all
                select 8 row_id, 789087 client_id, 4 status_id, to_date('21/12/2007 10:38','dd/mm/yyyy hh24:mi') from_date, to_date('21/12/2007 17:54','dd/mm/yyyy hh24:mi') todate from dual union all
                select 9 row_id, 789087 client_id, 4 status_id, to_date('21/12/2007 17:54','dd/mm/yyyy hh24:mi') from_date, to_date('21/12/2007 18:32','dd/mm/yyyy hh24:mi') todate from dual union all
                select 10 row_id, 789087 client_id, 4 status_id, to_date('21/12/2007 18:32','dd/mm/yyyy hh24:mi') from_date, to_date('22/12/2007 06:48','dd/mm/yyyy hh24:mi') todate from dual union all
                select 11 row_id, 123456 client_id, 5 status_id, to_date('21/12/2007 16:39','dd/mm/yyyy hh24:mi') from_date, null from dual union all
                select 12 row_id, 789087 client_id, 5 status_id, to_date('22/12/2007 06:48','dd/mm/yyyy hh24:mi') from_date, to_date('22/12/2007 10:53','dd/mm/yyyy hh24:mi') todate from dual union all
                select 13 row_id, 789087 client_id, 4 status_id, to_date('22/12/2007 10:53','dd/mm/yyyy hh24:mi') from_date, to_date('22/12/2007 11:51','dd/mm/yyyy hh24:mi') todate from dual union all
                select 14 row_id, 789087 client_id, 5 status_id, to_date('22/12/2007 11:51','dd/mm/yyyy hh24:mi') from_date, null from dual)
select row_id,
       client_id,
       status_id,
       from_date,
       todate,
       dense_rank() over (order by client_id, status_id, grp) rank_id
from   (select row_id,
               client_id,
               status_id,
               from_date,
               todate,
               row_number() over (order by client_id, from_date) - row_number() over (partition by status_id order by client_id, from_date) grp -- this is the tabibitosan step
        from   client) t1
order by client_id, from_date, status_id;

    ROW_ID  CLIENT_ID  STATUS_ID FROM_DATE        TODATE              RANK_ID
---------- ---------- ---------- ---------------- ---------------- ----------
         1     123456          4 20/12/2007 06:02 20/12/2007 06:07          1
         5     123456          4 20/12/2007 06:07 20/12/2007 06:50          1
         6     123456          4 20/12/2007 06:50 21/12/2007 10:38          1
         7     123456          4 21/12/2007 10:38 21/12/2007 04:39          1
        11     123456          5 21/12/2007 04:39                           2
         2     789087          4 20/12/2007 06:02 20/12/2007 06:07          3
         3     789087          4 20/12/2007 06:07 20/12/2007 06:50          3
         4     789087          4 20/12/2007 06:50 21/12/2007 10:38          3
         8     789087          4 21/12/2007 10:38 21/12/2007 05:54          3
         9     789087          4 21/12/2007 05:54 21/12/2007 06:32          3
        10     789087          4 21/12/2007 06:32 22/12/2007 06:48          3
        12     789087          5 22/12/2007 06:48 22/12/2007 10:53          5
        13     789087          4 22/12/2007 10:53 22/12/2007 11:51          4
        14     789087          5 22/12/2007 11:51                           6