Joe Celko's SQL for Smarties: Advanced SQL Programming (The Morgan Kaufmann Series in Data Management Systems)

Joe Celko's Trees and Hierarchies in SQL for Smarties (The Morgan Kaufmann Series in Data Management Systems)

SQL Antipatterns: Avoiding the Pitfalls of Database Programming (Pragmatic Programmers)

The Art of SQL

SQL Cookbook (Cookbooks (O'Reilly))

SQL Queries for Mere Mortals: A Hands-On Guide to Data Manipulation in SQL