I have certainly learned a lot over the years from other authors, and I thought I would share with you my fairly eclectic collection of favorite books (those that have informed my programming, in any case).

If you've got several queries that are all using DECODE and/or CASE to map one value to another, consider creating a mapping table and joining that into your queries instead. It will make them easier to maintain, and depending on your indexes it might even speed up some queries.