Little SQL Server Tricks: Aggregate Functions on Columns
Aggregate functions (like Min(), Max(), Sum(), etc.) are often used to calculate values in a SELECT statement. Instead of loading all the data and calculate the values for yourself, you let the database give you the answer. That is a lot faster and requires less typing. Aggregate functions are mostly used on rows. But did you know that SQL Server lets you use them on columns as well? This post shows how it is done what could be a simple solution for some tricky questions.

