Hello, excuse me the SQL language contains the exists double predicate correlated sub-query how to understand?
I was around a long time, and dizzy, feel difficult to understand, should how to understand will be clearer? 2

List at least learned 98030101 students learned all courses students student id
The Select DISTINC s # From SC SC1
Where not exists
(Select * From SC SC2
Where SC2. S #='98030101' and not the exists
(Select * From SC
Where c #=SC2. C # and s #=SC1. S #));
Thank you!!