Table schema:
CREATE TABLE Lessons (staff_id VARCHAR); CREATE TABLE Staff (staff_id VARCHAR, first_name VARCHAR, last_name VARCHAR)

Question: How long is the total lesson time taught by staff with first name as Janessa and last name as Sawayn?
SQL: 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"