What reference book should every DBA/Dev have?

SQL Server 2008 Internals by Kalen Delaney

My review is at: http://msmvps.com/blogs/robfarley/archive/2009/06/13/a-review-sql-server-2008-internals.aspx

Whole lot of good references here, but I would like to say what is your level of knowledge in SQL Server within DBA & Dev. arena. Depending upon your level it is ideal to pick & choose the books one-by-one. good luck.

"The Art of War".

All books mentioned are great..I have almost them. But I can not forget that two for me are fantastic. One is old but I hold very dear and do not know how I lived with SQL Server before it: the Kalen Delaney's "Inside SQL Server 2000". The other is a milestone in the routine management database, change the way you work, to see and understand your profession.. is Brad McGehee's "How to Became an Exceptional DBA"

SQL Pocket Guide by Jonathan Gennick (O'Reilly). Small, good examples, and includes: Oracle, DB2, SQL Server, MySQL, and PostgreSQL - never know when you may have to deal with one or all of them.