Skip to Main Content
Forums

SQL & PL/SQL

Announcement

For appeals, questions and feedback about Oracle Forums, please email oracle-forums-moderators_us@oracle.com. Technical questions should be asked in the appropriate category. Thank you!

Interested in getting your voice heard by members of the Developer Marketing team at Oracle? Check out this post for AppDev or this post for AI focus group information.

How to show a row has been "removed" from a table

RichardSquiresJun 1 2009 — edited Nov 4 2010
We maintain rows in a table with a version number which will determine the current set of accounts for a version. I need to be able to show the changes between the versions - when a row was ADDED, REMOVED or there was NO CHANGE. I can work out ADDED and NO_CHANGE without any problem, but I'm not sure how I can determine that a row has been REMOVED when it no longer exists in the next version.

I have provided an example piece of SQL below: 
with w_acct1 as
(select 'A1' acct, 0 vers from dual
 union all
 select 'A2' acct, 0 vers from dual
 union all
 select 'A3' acct, 0 vers from dual
 union all
 select 'A1' acct, 1 vers from dual
 union all
 select 'A2' acct, 1 vers from dual
 union all
 select 'A1' acct, 2 vers from dual
 union all
 select 'A4' acct, 2 vers from dual)
select a.*,
       nvl(lead(acct) over (partition by acct order by vers desc),'NULL') ld,
       case when lead(acct) over (partition by acct order by vers desc) is null then
               'ADDED'
           when lead(acct) over (partition by acct order by vers desc) = acct then
               'NO_CHANGE'
           else
               'REMOVED'
           end add_remove
from w_acct1 a
order by vers,acct
Which gives me the following result:

ACCT VERS LD ADD_REMOVE
A1 0 NULL NEW
A2 0 NULL NEW
A3 0 NULL NEW
A1 1 A1 NO_CHANGE
A2 1 A2 NO_CHANGE
A1 2 A1 NO_CHANGE
A4 2 NULL NEW

The result I want is:

ACCT VERS LD ADD_REMOVE
A1 0 NULL NEW
A2 0 NULL NEW
A3 0 NULL NEW
A1 1 A1 NO_CHANGE
A2 1 A2 NO_CHANGE
A3 1 NULL REMOVED
A1 2 A1 NO_CHANGE
A2 2 NULL REMOVED
A4 2 NULL NEW

Note the REMOVED rows associated with the version even though they don't exist in the dataset for that version number.

Can this be done with analytic functions or some other cool Oracle feature I'm missing?

Regards

Richard
This post has been answered by Aketi Jyuuzou on Jun 1 2009
Jump to Answer

Comments

BluShadow
You can't know about a row being removed unless you have a record of that row somewhere, either as a copy of your old data (see example below) or you've recorded the information using delete triggers etc.
SQL> ed
Wrote file afiedt.buf

  1  with old_data as (select 1 as id, 'A' as dta from dual union all
  2                     select 2, 'B' from dual union all
  3                     select 3, 'C' from dual)
  4      ,new_data as (select 1 as id, 'A' as dta from dual union all
  5                    select 3, 'X' from dual union all
  6                    select 4, 'Y' from dual)
  7  --
  8      ,ins_upd as (select * from new_data minus select * from old_data)
  9      ,del_upd as (select * from old_data minus select * from new_data)
 10      ,upd as (select id from ins_upd intersect select id from del_upd)
 11      ,ins as (select id from ins_upd minus select id from upd)
 12      ,del as (select id from del_upd minus select id from upd)
 13  --
 14  select 'Inserted' as action, null as old_id, null as old_dta, new_data.id as new_id, new_data.dta as new_dta
 15  from new_data join ins on (ins.id = new_data.id)
 16  union all
 17  select 'Updated', old_data.id, old_data.dta, new_data.id, new_data.dta
 18  from old_data join new_data on (old_data.id = new_data.id)
 19                join upd on (upd.id = new_data.id)
 20  union all
 21  select 'Deleted', old_data.id as old_id, old_data.dta as old_dta, null as new_id, null as new_dta
 22  from old_data join del on (del.id = old_data.id)
 23  union all
 24  select 'No Change' as action, new_data.id as old_id, new_data.dta as old_dta, new_data.id as new_id, new_data.dta as new_dta
 25  from new_data where id not in (select id from ins_upd union all
 26*                                select id from del_upd)
SQL> /

ACTION        OLD_ID O     NEW_ID N
--------- ---------- - ---------- -
Inserted                        4 Y
Updated            3 C          3 X
Deleted            2 B
No Change          1 A          1 A

SQL>
1 person found this helpful
Aketi Jyuuzou
Answer
I used OLAP B-)

My OLAP articles (in Japanese)
http://www.geocities.jp/oraclesqlpuzzle/oow2009-olap-model.html
http://codezine.jp/article/corner/71
create table w_acct1 as
select 'A1' acct, 0 vers from dual union all
select 'A2' acct, 0 vers from dual union all
select 'A3' acct, 0 vers from dual union all
select 'A1' acct, 1 vers from dual union all
select 'A2' acct, 1 vers from dual union all
select 'A1' acct, 2 vers from dual union all
select 'A4' acct, 2 vers from dual;

select acct,vers,
case when appearCnt=1 and preCnt = 0 then 'null'
     when appearCnt=preCnt then 'null'
     else acct end as LD,
case when appearCnt=1 and preCnt = 0 then 'NEW'
     when appearCnt=preCnt then 'REMOVED'
     else 'NO_CHANGE' end as ADD_REMOVE
from (select a.acct,b.vers,
      count(b.acct)
      over(partition by a.acct order by b.vers) as appearCnt,
      count(b.acct)
      over(partition by a.acct
           order by b.vers rows between unbounded preceding
                                    and 1 preceding) as preCnt,
      Lag(b.acct) over(partition by a.acct order by b.vers) as LagVal
        from (select distinct acct from w_acct1) a
        Left Join w_acct1 b
      partition by (b.vers)
          on a.acct = b.acct)
 where appearCnt > preCnt
    or LagVal is not null
order by vers,acct;

AC  VERS  LD    ADD_REMOV
--  ----  ----  ---------
A1     0  null  NEW      
A2     0  null  NEW      
A3     0  null  NEW      
A1     1  A1    NO_CHANGE
A2     1  A2    NO_CHANGE
A3     1  null  REMOVED  
A1     2  A1    NO_CHANGE
A2     2  null  REMOVED  
A4     2  null  NEW
Marked as Answer by RichardSquires · Sep 27 2020
fac586
or some other cool Oracle feature I'm missing?
Workspace Manager?
1 - 3
Locked Post
New comments cannot be posted to this locked post.

Post Details

Locked on Jun 29 2009
Added on Jun 1 2009
3 comments
1,591 views