Hello Anton,
As I see it, It's important to understand what you want to do with the data. do you need to present in the UI the results of the 1st data source? the 2nd? etc.
If no user interaction is involved between getting the results of the 1st and 2nd data sources, it may be better to have one function on the DB return all the results required in step 2 (so you don't have to think of iterations in VC).
But it all depends on the specifics of your scenario, I'm currently not sure I can say what's best. Maybe we could start by: why do we need two separate calls to the DB?
Thanks,
Udi