Show the authors who have submissions to more than one workshop.
CREATE TABLE submission (Author VARCHAR, Submission_ID VARCHAR); CREATE TABLE acceptance (Submission_ID VARCHAR, workshop_id VARCHAR)
[SQL] 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 [/SQL]