Let us see how to login to sysdba users:

Here I would check the Scott is available or not

screen-1:

SQL> select username,account_status from dba_users where username='SCOTT';
USERNAME ACCOUNT_STATUS
SCOTT OPEN

Open another screen and login with Scott user

SQL> select * from dept;
DEPTNO DNAME LOC
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON

Here we have executed the update query. Now this row's contention lock is enabled till the user gives commit or rollback.

SQL> update dept set dname='ADMIN' where deptno=40;

1 row updated.

Here I will check on sysadmin to find the locked objects using below query

SQL> col object_name for a25
select
 oracle_username,
 os_user_name,
 locked_mode,
 object_name,
 object_type
from
 V$locked_object a,dba_objects b
where 
 a.object_id=b.object_id;SQL> SQL>   2    3    4    5    6    7    8    9   10  

+SQL> set lines 120
SQL> /

Here the lock mode no is 3

Types of locks