Should be something like this (http://msdn2.microsoft.com/en-us/library/aa258235(SQL.80).aspx) ?

USE pubs

GO

SELECT Category =

CASE type

WHEN 'popular_comp' THEN 'Popular Computing'

WHEN 'mod_cook' THEN 'Modern Cooking'

WHEN 'business' THEN 'Business'

WHEN 'psychology' THEN 'Psychology'

WHEN 'trad_cook' THEN 'Traditional Cooking'

ELSE 'Not yet categorized'

END,

CAST(title AS varchar(25)) AS 'Shortened Title',

price AS Price

FROM titles

WHERE price IS NOT NULL

ORDER BY type, price

COMPUTE AVG(price) BY type

GO