What are the names , themes , and number of singers for every concert ?
select t2.concert_name ,  t2.theme ,  count(*) from singer_in_concert as t1 join concert as t2 on t1.concert_id  =  t2.concert_id group by t2.concert_id
select t2.concert_name ,  t2.theme ,  count(*) from singer_in_concert as t1 join concert as t2 on t1.concert_id  =  t2.concert_id group by t2.concert_id
[{'concert_Name': 'Auditions', 'Theme': 'Free choice', 'count(*)': 3}, {'concert_Name': 'Super bootcamp', 'Theme': 'Free choice 2', 'count(*)': 2}, {'concert_Name': 'Home Visits', 'Theme': 'Bleeding Love', 'count(*)': 1}, {'concert_Name': 'Week 1', 'Theme': 'Wide Awake', 'count(*)': 1}, {'concert_Name': 'Week 1', 'Theme': 'Happy Tonight', 'count(*)': 2}, {'concert_Name': 'Week 2', 'Theme': 'Party All Night', 'count(*)': 1}]