How many detentions are there in record?
select count(*) from detention
Show me the last name of teachers that were in any detentions.
select t2.last_name from detention as t1 join teachers as t2 on t1.teacher_id = t2.teacher_id
Give me the start and end dates of Schultz's ones.
select t1.datetime_detention_start, datetime_detention_end from detention as t1 join teachers as t2 on t1.teacher_id = t2.teacher_id where t2.last_name = "Schultz"