I was recently asked if QueryADataset supported Common Table Expressions.  After looking at the documentation and understanding the benefit it brings (like PIVOT and UNPIVOT), I decided to it was possible. 

I've almost got it working.  There's just 1 test case (multiple initial results and recursive queries) that I need to add support for.

I'm also looking at adding ranking functions and support for the OVER qualifier.

Should be in the next update.