结果应如下所示:
Doctors_have_no_patients
Doctor2
Doctor3
Doctor5
表格
Doctor table called `Doctors`
**DoctorID**
Doctor1
Doctor2
Doctor3
Doctor4
Doctor5
Booking table called `Bookings`
PatientID DoctorID Date
Patient1 Doctor1 etc.
Patient2 Doctor4 etc.
Patient3 Doctor1 etc.
我应该使用 distinct
或者其他的东西?喜欢:
select Bookings.DoctorID as Doctors_have_no_patients count(distinct(Bookings.PatientID))...
最佳答案
您可以使用 not in (在本例中也可以使用 not unique)
没有病人的医生数量
select count(*) from Doctors
where DoctorId not in (select doctorID from bookings);
医生ID
select DoctorID from Doctors
where DoctorId not in ( select doctorID from bookings);
关于php - 如何统计没有患者预约的医生?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37171529/