Check and release lock on tables

Good queries to keep here.

To check the existing locked create dby a user:
select a.object_name, b.oracle_username, b.os_user_name,c.sid, c.serial#,c.terminal, d.sql_text
from sys.dba_objects a,
v$locked_object b,
v$session c,
v$sqltext d
where a.object_id = b.object_id
and c.sid = b.session_id
and c.sql_hash_value = d.hash_value;

To remove the lock by killing a session:
alter system kill session 'c.sid, c.serial#'';