Show each author and the number of workshops they submitted to.
create table submission (author varchar, submission_id varchar, PRIMARY KEY (author)); create table acceptance (workshop_id varchar, submission_id varchar, PRIMARY KEY (workshop_id))
select t2.author, count(distinct t1.workshop_id) from acceptance as t1 join submission as t2 on t1.submission_id = t2.submission_id group by t2.author