instruction: how many patients have received nitroglycerin since 6 years ago within the same hospital visit after receiving anticonvulsant - gabapentin?
response: SELECT COUNT(DISTINCT t1.uniquepid) FROM (SELECT patient.uniquepid, treatment.treatmenttime, patient.patienthealthsystemstayid FROM treatment JOIN patient ON treatment.patientunitstayid = patient.patientunitstayid WHERE treatment.treatmentname = 'anticonvulsant - gabapentin' AND DATETIME(treatment.treatmenttime) >= DATETIME(CURRENT_TIME(), '-6 year')) AS t1 JOIN (SELECT patient.uniquepid, treatment.treatmenttime, patient.patienthealthsystemstayid FROM treatment JOIN patient ON treatment.patientunitstayid = patient.patientunitstayid WHERE treatment.treatmentname = 'nitroglycerin' AND DATETIME(treatment.treatmenttime) >= DATETIME(CURRENT_TIME(), '-6 year')) AS t2 WHERE t1.treatmenttime < t2.treatmenttime AND t1.patienthealthsystemstayid = t2.patienthealthsystemstayid