CREATE TABLE Lessons (staff_id VARCHAR2)
CREATE TABLE Staff (staff_id VARCHAR2, first_name VARCHAR2, last_name VARCHAR2)

What is average lesson price taught by staff with first name as Janessa and last name as Sawayn?
SELECT AVG(price) 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"
SELECT AVG("price") FROM "Lessons" "T1" JOIN "Staff" "T2" ON "Janessa" = "T2"."first_name" AND "Sawayn" = "T2"."last_name" AND "T1"."staff_id" = "T2"."staff_id"