SELECT id, 
  DECODE(customer_id, 'AOL', 'America Online') Company,
  order_date
FROM test2
WHERE ROWNUM < 21
/
 
 
SELECT program_id, 
       DECODE(customer_id,
              'AOL', 'America Online',
              'TW', 'Time Warner',
              'ORCL', 'Oracle Corporation',
              'NetApp', Network Appliances',
       order_date
FROM test2
WHERE ROWNUM < 21
/
 
 
decode with default
 
SELECT program_id, 
       DECODE(customer_id,
              'AOL', 'America Online',
              'TW', 'TIME Warner',
              'ORCL', 'Oracle Corporation',
              'NetApp', Network Appliances',
              'OTHER'
       order_date
FROM test2
WHERE ROWNUM < 21
/