Oracle从审计表中获得新的价值

Question

Say I have an audit table structure kind of like this (simplified).

OID,VALUE,CHANGED_DATE

and what I would like to do is write a query that, for each VALUE change, gives me the following output.

OLD_VALUE,NEW_VALUE,CHANGED_DATE

How would I go about doing that? So, for example, if I had

OID|VALUE|CHANGED_DATE
----------------------
1  |ABC  |15-JAN-18
2  |DEF  |22-JUN-18
3  |XYZ  |16-JUL-18

I would like to see output like:

OLD_VALUE|NEW_VALUE|CHANGED_DATE
--------------------------------
ABC      |DEF      |22-JUN-18
DEF      |XYZ      |16-JUL-18

Answer 1

Use lag() :

select oid, lag(oid) over (order by changed_date) as prev_oid, changed_date
from t;

This code includes all three rows. If you want to eliminate the first:

select *
from (select oid, lag(oid) over (order by changed_date) as prev_oid, changed_date
      from t
     ) t
where prev_oid is not null;

Answer 2

You want lead() :

select t.*
from (select oid, lead(value) over (order by changed_date) as next_value, changed_date
      from table 
     ) t
where next_value is not null;