Find the names of all procedures such that the cost is less than 5000 and physician John Wen was trained in.
SELECT name FROM procedures WHERE cost  <  5000 INTERSECT SELECT T3.name 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"
cost less than 5000 refers to cost < 5000; physician John Wen was trained in refers to a JOIN operation between physician and trained_in tables filtering by physician.name = 'John Wen'; finding names of all procedures requires selecting the name column from the procedures table; INTERSECT is used to combine results satisfying both conditions.