Question

Hi I have a select query where I am selecting 2 different date columns from the table, I need to merge them into one column in the result and order in the descending order of the date.
The query looks like following:

select work_order_no,install_remove_type,removed_item_id,installed_item_id,
       removed_performed_on as irdate, 
       installed_performed_on as irdate 
  from install_remove_items 
 where work_order_no is not null  
   and (installed_item_id = 'IID000174096' or removed_item_id= 'IID000174096')

The result of the above query is that there are 2 columns created

irdate – for removed_performed_on

and

irdate_1 – for installed_performed_on

which is not the way I want it..How do I have the date related data in the ‘irdate’ column and also sorted in desc order?

Update:

sample data in install_remove_items table (4 records for 4 Action types in INSTALL_REMOVE_TYPE field):

 ir_id: xxxxyyyy5555,  install_remove_type= 'INSTALL', workOrderno = 22335522, installed_item_id = IID000174096, installed_performed_on = '11/10/2012', removed_item_id = null, removed_performed_on = null.

 ir_id: xxxxyyyy3333, install_remove_type= 'REMOVE', workOrderno = 223542, installed_item_id = null, installed_performed_on = null, removed_item_id = IID000174096, removed_performed_on = '11/12/2012'.

 ir_id: xxxxyyyy1111,  install_remove_type= 'WORKEDON', workOrderno = 111111, installed_item_id = null, installed_performed_on = null, removed_item_id = IID000174096, removed_performed_on = '11/13/2012'.

 ir_id: xxxxyyyy2222, install_remove_type= 'REPLACED', workOrderno = 444444, installed_item_id = IID000174096, installed_performed_on = 11/15/2012, removed_item_id = IID000174096, removed_performed_on = '11/14/2012'.

So there are 4 types of Action, ‘removed’ fields are populated for REMOVE action, ‘install’ fields for INSTALL action, both fields for REPLACED action and ‘removed’ fields for WORKEDON action.

I want to write a query to find what kind of action out of the four was performed last (compared to today’s date or an input date value) based on the install_performed_on and removed_performed_on date (and also get that date).

Hope this makes things clear.

I know union may be good, but currently the Java API we have for SQL doesnt support union, so I may have to do a combination of SQL and JAVA code to achieve my output.

Thanks in advance.

Answer 1

its not totally clear what you want without you putting the sample data you want. but would this be it ?

select *
  from (select work_order_no,install_remove_type,installed_item_id,
                   installed_performed_on as irdate 
              from install_remove_items 
             where work_order_no is not null  
               and installed_item_id = 'IID000174096'
            union all
            select work_order_no,install_remove_type,removed_item_id,
                   removed_performed_on as irdate
              from install_remove_items 
             where work_order_no is not null  
               and removed_item_id= 'IID000174096')
         order by irdate desc;

revised to as per your sample:

SQL> select *
  2    from (select workOrderno, install_remove_type,
  3                 case
  4                   when installed_performed_on > removed_performed_on
  5                     or removed_performed_on is null then ir.installed_performed_on
  6                   else removed_performed_on
  7                 end last_action_date,
  8                 coalesce(ir.installed_item_id,ir.removed_item_id)  item_id
  9            from install_remove_items ir
 10           where workOrderno is not null
 11             and (installed_item_id = 'IID000174096' or removed_item_id= 'IID000174096')
 12           order by last_action_date desc )
 13   where rownum = 1
 14  /

WORKORDERNO INSTALL_RE LAST_ACTI ITEM_ID
----------- ---------- --------- --------------------
     444444 REPLACED   15-NOV-12 IID000174096

or a list for every item you can do like this:

SQL> select * from install_remove_items;

IR_ID                INSTALL_RE WORKORDERNO INSTALLED_ITEM_ID    INSTALLED REMOVED_ITEM_ID      REMOVED_P
-------------------- ---------- ----------- -------------------- --------- -------------------- ---------
xxxxyyyy5555         INSTALL       22335522 IID000174096         10-NOV-12
xxxxyyyy3333         REMOVE          223542                                IID000174096         12-NOV-12
xxxxyyyy1111         WORKEDON        111111                                IID000174096         13-NOV-12
xxxxyyyy2222         REPLACED        444444 IID000174096         15-NOV-12 IID000174096         14-NOV-12
3242                 REMOVE              43                                IID000174097         14-DEC-12
123                  INSTALL            123 IID000174097         15-NOV-12

6 rows selected.

SQL> select workorderno, install_remove_type, item_id, last_action_date
  2    from (select l.*,
  3                  row_number() over(partition by item_id order by last_action_date desc) rn
  4             from (select workorderno, install_remove_type,
  5                           case
  6                             when installed_performed_on > removed_performed_on or
  7                                  removed_performed_on is null then
  8                              ir.installed_performed_on
  9                             else
 10                              removed_performed_on
 11                           end last_action_date,
 12                           coalesce(ir.installed_item_id, ir.removed_item_id) item_id
 13                      from install_remove_items ir
 14                     where workorderno is not null) l)
 15   where rn = 1;

WORKORDERNO INSTALL_RE ITEM_ID              LAST_ACTI
----------- ---------- -------------------- ---------
     444444 REPLACED   IID000174096         15-NOV-12
         43 REMOVE     IID000174097         14-DEC-12