Depends on what you're into, but from the database angle:
Learning SQL is a really excellent intro, and probably covers the majority of what your average developer is going to ever need to know about SQL ( http://shop.oreilly.com/product/9780596520847.do )
SQL and Relational Theory gives you more background on relational theory - basically gives a more academic background for existing practitioners of SQL. Date is pretty dry author with a few hangups, but it's largely good solid stuff ( http://shop.oreilly.com/product/0636920022879.do )
I've not read the book so can't comment on it specifically, but I can tell you about Date, who is an eminent author in the field. His 'An Introduction to Database Systems' is perhaps the best book to read if you want to get an idea of how DBMSs work internally. Anyway:
- He really dislikes SQL (His books often use Tutorial D, which is a language Date created to represent what a good relational query language would look like).
- He really hates the use of null values.
- He's of an academic bent - dryish, but still perfectly readable.
- I would say that he tends to gloss over performance issues that get in the way of ideal database schema design, viewing them as implementation issues (which is true, but in reality, all DBMS products have weaknesses, and at some point you'll probably have to make compromises in your schema design).
With this said, I would read his book. He'll tell you the best way to do things, if you ignore performance. This puts you in a good position to start out from a pure, ideal implementation from which you can compromise when you have to. I much prefer this to a less-educated ad-hoc approach.
Learning SQL is a really excellent intro, and probably covers the majority of what your average developer is going to ever need to know about SQL ( http://shop.oreilly.com/product/9780596520847.do )
SQL and Relational Theory gives you more background on relational theory - basically gives a more academic background for existing practitioners of SQL. Date is pretty dry author with a few hangups, but it's largely good solid stuff ( http://shop.oreilly.com/product/0636920022879.do )
Oracle Essentials is a good solid introduction to Oracle, and gives a useful bit of background on how database management systems work ( http://shop.oreilly.com/product/9780596514549.do )
For other subjects:
Code Complete needs little introduction ( http://shop.oreilly.com/product/9780735619678.do )
I've only just started reading Version Control with Git, but it seems pretty good so far, and is well-reviewed ( http://shop.oreilly.com/product/9780596520137.do )