Dear Mynda,
I really appreciate your courses. They are very thorough, and I always learn something new.
In topic 2.05 you mention that we should do the transformations in the sample query rather than in the final query. I think I have not really understood why 
Could you please clarify why this is better - and would I run into trouble if I filtered my columns in the final query instead?
Thank you in advance.
Kind regards,
Peter
Hi Peter,
If you need to do a transformation like unpivot, then this needs to be done at the sample query level, i.e. before the data gets to the final query. Because you can't unpivot once all of the files have been combined. More simple transformations, like filters, can be applied at the final query stage if you want. It makes no difference whether you do this at the sample or the final query.
I hope that clarifies things, but shout if you have more questions.
Mynda
Hi Mynda,
Thank you for your reply. I get it. I think that so far I have only been using filters and thus not experienced any problems.
Kind regards,
Peter
