instruction: provide the number of patients whose diagnoses long title is hydronephrosis and drug route is sc?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id WHERE diagnoses.long_title = "Hydronephrosis" AND prescriptions.route = "SC"