SQL plus enviroment

In order for DBMS_OUTPUT to work, the following command must be issued
SQL > set serveroutput on

The set serveroutput on size 1000000 ..... the set the default buffer size to be as large as possible...

Set trimspool on ensures that, when spooling text, lines will be blank-trimmed and not fixed width...

set long 5000 sets the default number of bytes displayed when selecting LONG and CLOB

set pagesize 9999 sets the pagesize, which controls how frequently sql*plus prints out headings, to big number (we get one set of heading per page).