Counting Parents and Children with Count Distinct
The aggregate functions in SQL Server (min, max, sum, count, average, etc.) are great tools for reporting and business analysis. But sometimes, you need to tweak them just a little bit to get exactly the results you need. For example, if your manager came to you and asked for a report on how many sales have been made to your clients and how large they were, would you know how to get the data you need efficiently? Mark ran into something like this recently and here's the approach he took to solve the problem.
