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
Show the name and theme for all concerts and the number of singers in each 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
Show the name and theme for all concerts and the number of singers in each concert .