CREATE TABLE trained_in (physician VARCHAR, treatment VARCHAR)
CREATE TABLE physician (employeeid VARCHAR, name VARCHAR)
CREATE TABLE procedures (cost INT, code VARCHAR)

What is the average cost of procedures that physician John Wen was trained in?
SELECT AVG(T3.cost) FROM physician AS T1 JOIN trained_in AS T2 ON T1.employeeid = T2.physician JOIN procedures AS T3 ON T3.code = T2.treatment WHERE T1.name = "John Wen"
SELECT AVG("T3"."cost") FROM "physician" AS "T1" JOIN "trained_in" AS "T2" ON "T1"."employeeid" = "T2"."physician" JOIN "procedures" AS "T3" ON "T2"."treatment" = "T3"."code" WHERE "John Wen" = "T1"."name"