You must specify sid and serial identifing the session to kill. You can find these values querying the V$SESSION view:

SQL> SELECT sid, serial#, username from v$session;

Killing a session is very simple:

SQL> ALTER system KILL session ‘<sid,serial>’;

DBMS_OUTPUT is a package that let you able to write some output on the screen. In SQL*Plus you can enable the output with this command:

SQL> SET serverout ON

All output will be written in a buffer. The default size of the buffer is 20,000 bytes. If you want a different buffer size you must use the enable procedure:

DBMS_OUTPUT.ENABLE (
buffer_size IN INTEGER DEFAULT 20000);

The defualt buffer size is 20,000 bytes, the maximum size is 1,000,000 bytes and the minimum is 2,000. To enable an unlimited buffer size you must …