instruction: what is the four most frequently ordered procedure for a patient with an age 40s?
response: SELECT t1.treatmentname FROM (SELECT treatment.treatmentname, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM treatment WHERE treatment.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.age BETWEEN 40 AND 49) GROUP BY treatment.treatmentname) AS t1 WHERE t1.c1 <= 4