When should I use cross apply over inner join?

Question

What is the main purpose of using CROSS APPLY?

I have read (vaguely, through posts on the Internet) that cross apply can be more efficient when selectin

Answer 1

This is perhaps an old question, but I still love the power of CROSS APPLY to simplify the re-use of logic and to provide a "chaining" mechanism for results.

I've provided a SQL Fiddle below which shows a simple example of how you can use CROSS APPLY to perform complex logical operations on your data set without things getting at all messy. It's not hard to extrapolate from here more complex calculations.

http://sqlfiddle.com/#!3/23862/2