oracle sql case in where clause code example

Example: oracle case

SELECT product_id, product_type_id,
  CASE product_type_id
    WHEN 1 THEN 'Book'
    WHEN 2 THEN 'Video'
    WHEN 3 THEN 'DVD'
    WHEN 4 THEN 'CD'
    ELSE 'Magazine'
  END
FROM products;