Order by multiple columns and ROWNUM

Question

Hi -
I am trying to use rownum in colloboration with order by multiple columns but I guess I am doing something wrong
and I am always getting a single row per emp_id rather than getting single row for a particular emp_id,role_id,inst_id,exp_date.
Below is the table ddl and data insertion script.
====
create table tab_details
(emp_id varchar2(50),
role_id integer,
inst_id integer,
exp_date date,
chk_ind char(1),
trans_type char(1),
trans_date date);
insert all
into tab_details values ('JBRAMS',12,4556,'07/15/2011','Y','U','05/21/2011')
into tab_details values ('JBRAMS',12,4556,'07/15/2011','N','U','05/22/2011')
into tab_details values ('JBRAMS',12,4556,'07/15/2011','N','D','05/23/2011')
into tab_details values ('JBRAMS',12,4556,'07/15/2011','N','U','05/24/2011')
into tab_details values ('KCASOT',98,9001,'08/03/2011','Y','U','04/11/2011')
into tab_details values ('KCASOT',98,9001,'08/03/2011','N','U','04/12/2011')
into tab_details values ('KCASOT',98,9001,'08/03/2011','N','U','04/13/2011')
into tab_details values ('JBRAMS',43,7875,'06/28/2011','Y','U','03/19/2011')
into tab_details values ('JBRAMS',43,7875,'06/28/2011','N','U','03/20/2011')
into tab_details values ('BHAYEN',28,4098,'07/01/2011','Y','U','02/13/2011')
into tab_details values ('BHAYEN',28,4098,'07/01/2011','N','U','02/14/2011')
into tab_details values ('BHAYEN',28,4098,'07/01/2011','N','D','02/15/2011')
into tab_details values ('BHAYEN',28,4098,'07/01/2011','Y','U','02/16/2011')
into tab_details values ('BHAYEN',28,4098,'07/01/2011','N','U','02/17/2011')
into tab_details values ('BHAYEN',28,4098,'07/01/2011','N','U','02/18/2011')
select * from dual;
commit;
====
So for the first four rows inserted above, I need only following row:
'JBRAMS',12,4556,'07/15/2011','N','U','05/22/2011'
Basically, I need only the rows with chk_ind='N' and trans_type<>'D' and if there is a row with
chk_ind='N' and trans_type='U' after trans_type='D" for a emp_id,role_id,inst_id,exp_date then it should be ignored.
Following are the only rows I am looking for:
'JBRAMS',12,4556,'07/15/2011','N','U','05/22/2011'
'KCASOT',98,9001,'08/03/2011','N','U','04/12/2011'
'JBRAMS',43,7875,'06/28/2011','N','U','03/20/2011'
'BHAYEN',28,4098,'07/01/2011','N','U','02/14/2011'
'BHAYEN',28,4098,'07/01/2011','N','U','02/17/2011'
Please share your thought over this.
Thanks,
-Seenu

Answer 1

Hi, Seenu,
Seenu001 wrote:
Hi -
I am trying to use rownum in colloboration with order by multiple columns but I guess I am doing something wrong
and I am always getting a single row per emp_id rather than getting single row for a particular emp_id,role_id,inst_id,exp_date.Thanks for posting the CREATE TABLE and INSERT statements. It would help if you posted your query, too: even if it's not qute right, it could help to understand the problem, and modifying it might be more efficient than writing a completely new query.
What are the multiple columns you are sorting on? Why isn't trans_date enough?
Here's one way:
WITH     got_okay     AS
     SELECT     t.*
     ,     CASE
               WHEN  LAG (chk_ind)    OVER ( PARTITION BY  emp_id
                                 ,           role_id
                                 ,           inst_id
                                 ,           exp_date
                                 ORDER BY      trans_date
                                  ) = 'N'
               AND   LAG (trans_type) OVER ( PARTITION BY  emp_id
                                 ,           role_id
                                 ,           inst_id
                                 ,           exp_date
                                 ORDER BY      trans_date
                                  ) IN ('D', 'U')
               THEN  0
               ELSE  1
          END          AS okay
     FROM     tab_details     t
SELECT       *     -- or list all columns except d_cnt
FROM       got_okay
WHERE       chk_ind     = 'N'
AND       trans_type     != 'D'
AND       (     trans_type     != 'U'
       OR     okay          = 1
;