All of us who work with relational databases have learned (or are learning) that SQL is different. Eliciting the desired results, and doing so efficiently, involves a tedious process partly characterized by learning unfamiliar paradigms, and finding out that some of our most familiar programming patterns don't work here. What are the most common antipatterns you've seen (or your self committed), whether generic or product-specific, whether in SQL statements directly, or in the ways applications build and apply them?