Which workshops happened in New York USA?
select name from workshop where venue = "New york USA"
How many workshops have been held?
select count(*) from workshop
How many authors have submitted to more than one workshop?
select count(distinct t2.author) from acceptance as t1 join submission as t2 on t1.submission_id = t2.submission_id group by t2.author having count(distinct t1.workshop_id) > 1
Please show their names.
select t2.author from acceptance as t1 join submission as t2 on t1.submission_id = t2.submission_id group by t2.author having count(distinct t1.workshop_id) > 1