Group the patients by the physician treating them.
select * from physician as t1 join patient as t2 on t1.employeeid = t2.pcp group by t1.employeeid
How many patients is each physician taking care of?
select count(*) from physician as t1 join patient as t2 on t1.employeeid = t2.pcp group by t1.employeeid
For each physician, return his or her name and the number of patients.
select t1.name, count(*) from physician as t1 join patient as t2 on t1.employeeid = t2.pcp group by t1.employeeid