finding last dml done in database

[launchpad]

It can be as simple as this :
select sql_text, hash_value, first_load_time from V$sqlarea order by first_load_time desc ;

This should give you all latest SQL that ran in the database..
In case you want to dig deep, get the hash value and find in sql_text as

select sql_text fromk v$sql_text where hash_value = &hash_value order by piece;