When the job can't be done with a simple query you have to do it with an advanced query. For that you have to figure out how things exactly work in SQL. This is sometimes, when queries become more complex, very time consuming. You have to know a lot about SQL. I think the gap between the simple query and the advanced query is to big.
It would be very helpfull if there was a graphical, SQL-SERVER or ACCESS like, query designer. This would speed up the development time for advanced Queries. (See Attachment). Additionaly, it would be great if the Output Structure, with the selected columns, will be created automaticly .