I'm just going to say it straight out. I'm pessimistically optimistic that most really understand transaction concurrency in SQL Server. There is often significant confusion about transaction concurrency and contention options available to Developers -is it 'pessimistic', or 'optimistic', or in between? Everyone ‘sort of’ understands READ COMMITTED (RC). But do you sometimes feel 'dirty' as you attempt to 'repeatedly' read that phantasma? In order to reduce locking and blocking conflicts, some folks adopt SNAPSHOT ISOLATION (SI). And a few hardy stalwarts have ventured into the new world of READ COMMITTED SNAPSHOT ISOLATION (RCSI). In this session, we will explore the differences between the three, including a discussion about the positives and negatives of each option. We will discuss the effects of 'Dirty', 'Repeatable' and 'Phantom' reads, and why you may want to know which may be buried in your code. There will be code examples demonstrating the benefits and traps of each option.