How many patients' prescriptions are made by physician John Dorian?
create table patient (ssn varchar, PRIMARY KEY (ssn)); create table prescribes (patient varchar, physician varchar, PRIMARY KEY (patient)); create table physician (employeeid varchar, name varchar, PRIMARY KEY (employeeid))
select count(t1.ssn) from patient as t1 join prescribes as t2 on t1.ssn = t2.patient join physician as t3 on t2.physician = t3.employeeid where t3.name = "john dorian"