How long is the total lesson time taught by staff with first name as Janessa and last name as Sawayn?
create table lessons (staff_id varchar, PRIMARY KEY (staff_id)); create table staff (staff_id varchar, first_name varchar, last_name varchar, PRIMARY KEY (staff_id))
select sum(lesson_time) from lessons as t1 join staff as t2 on t1.staff_id = t2.staff_id where t2.first_name = "janessa" and t2.last_name = "sawayn"