Comment by alfet

The main advantage of using common table expressions is the improved readability and ease in maintenance of complex queries, after a while using them coming up with a solution for a complex query is quite easy. Regarding the performance of them, it depends on what you are trying to accomplish, some times theres some performance penalties but in my personal experience (using them in SQL Server) I have never run into a case where the performance isn't good, well that's not entirely true, in cases where you need to return large datasets CTE are never the best solution.