instruction: what were the four most common drugs that patients were prescribed within 2 months after being prescribed with carvedilol 25 mg po tabs until 3 years ago?
response: SELECT t3.drugname FROM (SELECT t2.drugname, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM (SELECT patient.uniquepid, medication.drugstarttime FROM medication JOIN patient ON medication.patientunitstayid = patient.patientunitstayid WHERE medication.drugname = 'carvedilol 25 mg po tabs' AND DATETIME(medication.drugstarttime) <= DATETIME(CURRENT_TIME(), '-3 year')) AS t1 JOIN (SELECT patient.uniquepid, medication.drugname, medication.drugstarttime FROM medication JOIN patient ON medication.patientunitstayid = patient.patientunitstayid WHERE DATETIME(medication.drugstarttime) <= DATETIME(CURRENT_TIME(), '-3 year')) AS t2 ON t1.uniquepid = t2.uniquepid WHERE t1.drugstarttime < t2.drugstarttime AND DATETIME(t2.drugstarttime) BETWEEN DATETIME(t1.drugstarttime) AND DATETIME(t1.drugstarttime, '+2 month') GROUP BY t2.drugname) AS t3 WHERE t3.c1 <= 4