what were the three most frequent drugs that were prescribed to the patients 60 or above during the same month after they had been diagnosed with staphylococcus unspcfied in this year?
select t3.drug from ( select t2.drug, dense_rank() over ( order by count(*) desc ) as c1 from ( select admissions.subject_id, diagnoses_icd.charttime from diagnoses_icd join admissions on diagnoses_icd.hadm_id = admissions.hadm_id where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'staphylococcus unspcfied' ) and datetime(diagnoses_icd.charttime,'start of year') = datetime(current_time,'start of year','-0 year') ) as t1 join ( select admissions.subject_id, prescriptions.drug, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where admissions.age >= 60 and datetime(prescriptions.startdate,'start of year') = datetime(current_time,'start of year','-0 year') ) as t2 on t1.subject_id = t2.subject_id where t1.charttime < t2.startdate and datetime(t1.charttime,'start of month') = datetime(t2.startdate,'start of month') group by t2.drug ) as t3 where t3.c1 <= 3