How to find database usage for a specific application action A user is opening a page in our application which takes around 35 seconds.
I want to see what is happening in the database during this time. What's the best way to do this, doing a trace? 
Thanks!
Best scenario is only do this test and not let anything else run
on the server during the test.
If not isolate one application server for this purpose so you can
filter with host name or login (whatever is easier in your case).
Set up an extended event trace with the events you want to capture,
include necessary Global Fields.
Set up data storage type event_file so you can review the result later and even load
into a SQL Server database table.
Since you are capturing the trace under one minute I would not bother to
roll files.
If you are not familiar with Extended Event trace search for 'getting
started with extended events' and you will see a large amount of
useful resources.