Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE singer_in_concert (concert_id VARCHAR)
TABLE: CREATE TABLE concert (concert_name VARCHAR, theme VARCHAR, concert_id VARCHAR)

### Question ###
What are the names , themes , and number of singers for every concert ?

### Accurate SQL ###

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