SQL*Plus: Release 10.2.0.1.0 - Production on Ćar Eyl 26 09:22:22 2007

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-- Step A, 4 sessions
--
-- FROM SESSION - 1
SQL> conn hr/hr
Connected.
SQL> select employee_id from employees where rownum < 3 ;

EMPLOYEE_ID
-----------
        100
        101

SQL> update employees set salary = salary * 1.3
  2  where employee_id = 100 ;

1 row updated.

-- FROM SESSION - 2
SQL> conn hr/hr
Connected.
SQL> lock table employees in share mode ;

waiting..

-- FROM SESSION - 3
SQL> conn hr/hr
Connected.
SQL> update employees set salary = salary * 1.3
  2* where employee_id = 110 ;

waiting..

-- FROM SESSION - 4
SQL> conn / as sysdba
Connected.
SQL> set linesize 20000
SQL> @D:\oraclexe\app\oracle\product\10.2.0\server\RDBMS\ADMIN\utllockt.sql
..

WAITING_SESSION   LOCK_TYPE         MODE_REQUESTED MODE_HELD      LOCK_ID1    LOCK_ID2
----------------- ----------------- -------------- -------------- ---------   ---------------
38                None
   33             DML               Share          Row-X (SX)     12100    0
   37             DML               Row-X (SX)     Row-X (SX)     12100    0


..

-- Step B, 4 sessions
--
-- FROM SESSION - 1
SQL> rollback ;

Rollback complete.

-- @ SESSION - 2
Table(s) Locked.

message falls to prompt

-- @ SESSION - 3

still no action and waiting

-- FROM SESSION - 4
SQL> @D:\oraclexe\app\oracle\product\10.2.0\server\RDBMS\ADMIN\utllockt.sql
..

WAITING_SESSION   LOCK_TYPE         MODE_REQUESTED MODE_HELD      LOCK_ID1    LOCK_ID2
----------------- ----------------- -------------- -------------- --------    -----------------
33                None
   37             DML               Row-X (SX)     Share          12100    0

..

-- Step C, 4 sessions
--
-- FROM SESSION - 2
SQL> rollback ;

Rollback complete.

-- @ SESSION - 3

1 row updated.

message falls to prompt

-- FROM SESSION - 4
SQL> @D:\oraclexe\app\oracle\product\10.2.0\server\RDBMS\ADMIN\utllockt.sql
..

no rows selected

..