Summary
Report Sections in Yellowfin differ from many aspects of the Report Builder's data handling, such as drills, which modify the SQL statement. Instead of changing the SQL, Sections are entirely handled in Yellowfin's own post-processing.
Example
In other words, the SQL statement is exactly the same for this:
As it is for this:
Sections get built into the SQL statement as if they were any other column, Yellowfin simply cuts out the column from the final result and parses it out, which is done in post-processing.