mysql - 从与主 ID 键链接的其他表中添加名称

Question

我有 3 张桌子，分别称为 Doctor、Appointment 和 Person。我需要将医生的姓名添加到以下结果中：

使用此代码：

SELECT doctor.doctor_id, COUNT(appointment.appt_time) AS No_APP 
FROM doctor
LEFT JOIN appointment 
ON appointment.doctor_id = doctor.doctor_id
GROUP BY doctor.doctor_id;

我可以对其进行哪些修改，以便我可以使用它的医生姓名，这是我的表格列表（名称在带有医生 ID 的人员表中）：

Answer 1

SELECT
    doctor.doctor_id,
    person.last_name,
    COUNT(appointment.appt_time) AS No_APP 
FROM
    doctor
LEFT JOIN
    appointment  ON appointment.doctor_id = doctor.doctor_id
LEFT JOIN
    person  ON doctor.doctor_id = person.person_id
GROUP BY
    doctor.doctor_id,
    person.last_name;

或者你甚至可以跳过doctor表格：

SELECT
    person.person_id,
    person.last_name,
    COUNT(appointment.appt_time) AS No_APP 
FROM
    person
LEFT JOIN
    appointment ON appointment.doctor_id = person.person_id
GROUP BY
    person.person_id,
    person.last_name;