CREATE TABLE treatment (treatmentid NUMBER, patientunitstayid NUMBER, treatmentname CLOB, treatmenttime TIME)
CREATE TABLE cost (costid NUMBER, uniquepid CLOB, patienthealthsystemstayid NUMBER, eventtype CLOB, eventid NUMBER, chargetime TIME, cost NUMBER)
CREATE TABLE patient (uniquepid CLOB, patienthealthsystemstayid NUMBER, patientunitstayid NUMBER, gender CLOB, age CLOB, ethnicity CLOB, hospitalid NUMBER, wardid NUMBER, admissionheight NUMBER, admissionweight NUMBER, dischargeweight NUMBER, hospitaladmittime TIME, hospitaladmitsource CLOB, unitadmittime TIME, unitdischargetime TIME, hospitaldischargetime TIME, hospitaldischargestatus CLOB)
CREATE TABLE microlab (microlabid NUMBER, patientunitstayid NUMBER, culturesite CLOB, organism CLOB, culturetakentime TIME)
CREATE TABLE lab (labid NUMBER, patientunitstayid NUMBER, labname CLOB, labresult NUMBER, labresulttime TIME)
CREATE TABLE vitalperiodic (vitalperiodicid NUMBER, patientunitstayid NUMBER, temperature NUMBER, sao2 NUMBER, heartrate NUMBER, respiration NUMBER, systemicsystolic NUMBER, systemicdiastolic NUMBER, systemicmean NUMBER, observationtime TIME)
CREATE TABLE intakeoutput (intakeoutputid NUMBER, patientunitstayid NUMBER, cellpath CLOB, celllabel CLOB, cellvaluenumeric NUMBER, intakeoutputtime TIME)
CREATE TABLE diagnosis (diagnosisid NUMBER, patientunitstayid NUMBER, diagnosisname CLOB, diagnosistime TIME, icd9code CLOB)
CREATE TABLE medication (medicationid NUMBER, patientunitstayid NUMBER, drugname CLOB, dosage CLOB, routeadmin CLOB, drugstarttime TIME, drugstoptime TIME)
CREATE TABLE allergy (allergyid NUMBER, patientunitstayid NUMBER, drugname CLOB, allergyname CLOB, allergytime TIME)

during the last year count the number of patients who were diagnosed with infected pressure ulcer and did not come back to the hospital in the same month.
SELECT (SELECT COUNT(DISTINCT t1.uniquepid) FROM (SELECT patient.uniquepid, diagnosis.diagnosistime FROM diagnosis JOIN patient ON diagnosis.patientunitstayid = patient.patientunitstayid WHERE diagnosis.diagnosisname = 'infected pressure ulcer' AND DATETIME(diagnosis.diagnosistime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year')) AS t1) - (SELECT COUNT(DISTINCT t2.uniquepid) FROM (SELECT patient.uniquepid, diagnosis.diagnosistime FROM diagnosis JOIN patient ON diagnosis.patientunitstayid = patient.patientunitstayid WHERE diagnosis.diagnosisname = 'infected pressure ulcer' AND DATETIME(diagnosis.diagnosistime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year')) AS t2 JOIN patient ON t2.uniquepid = patient.uniquepid WHERE t2.diagnosistime < patient.hospitaladmittime AND DATETIME(patient.hospitaladmittime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year') AND DATETIME(t2.diagnosistime, 'start of month') = DATETIME(patient.hospitaladmittime, 'start of month'))
SELECT (SELECT COUNT(DISTINCT "patient"."uniquepid") FROM "diagnosis" JOIN "patient" ON "diagnosis"."patientunitstayid" = "patient"."patientunitstayid" WHERE "diagnosis"."diagnosisname" = 'infected pressure ulcer' AND DATETIME("diagnosis"."diagnosistime", 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year')) - (SELECT COUNT(DISTINCT "patient_2"."uniquepid") FROM "diagnosis" JOIN "patient" "patient_2" ON "diagnosis"."patientunitstayid" = "patient_2"."patientunitstayid" JOIN "patient" ON "diagnosis"."diagnosistime" < "patient"."hospitaladmittime" AND "patient"."uniquepid" = "patient_2"."uniquepid" AND DATETIME("diagnosis"."diagnosistime", 'start of month') = DATETIME("patient"."hospitaladmittime", 'start of month') AND DATETIME("patient"."hospitaladmittime", 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year') WHERE "diagnosis"."diagnosisname" = 'infected pressure ulcer' AND DATETIME("diagnosis"."diagnosistime", 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year'))