Isolation Levels

As a follow up to my NOLOCK blog I thought it would be a good idea to discuss the five different isolation levels in SQL Server. These are as follows:

NOLOCK!

Introduction

I see many developers writing SQL code and using NOLOCK as a "performance tool". I see NOLOCK spread liberally through scripts, applied to every single table as far as the eye can see. This technique is dangerous and I would like to share why.