Possibility to search system tags with an advanced query system

[Spartachetto]

It would be really useful to have the possibility to search not only for tag A AND tag B but also for tag A AND NOT tag B, or tag A OR tag B

I would value especially tag A AND NOT tag _B.
Some use cases:

• All the documents about client X and not about contracts
• All the photos about family and not about private

[depawlur]

+1 from me,
I would also like to be able to search for different files at the same time.
Let’s say keywords like “linux | windows” or “techno | prodigy | kmfdm | abba”

I used to use it all the times in google drive, really helped me with sharing.

[Spartachetto]

I was thinking that even this “simple” change in the interface would be a big improvement.
I’d love to have the opinion of an expert: @jan …!

My hypothesis of how to make it work would be:

1. automatic focus on “Select tags to filter by” as is already in #2105
2. start to search when the first tag in “… filter by” field is selected
3. allow to fill “… to exclude” even if "… filter by" is empty, yet do NOT start to search if “… filter by” is empty

Of course this change should keep into consideration also

Visualize useful synthetic information when user clicks 'Tags'

[Spiral]

I think this functionality to do an exclusive search would be great.