mysql在一条语句中删除多个具有左连接的表，导致fk冲突。例如，

Student       StudentDetail      
--------      ------------------------------
id, name      studentId, birthday, address

100 John       100      1/1/1982   A1
200 Scott      200      1/1/1978   A2
300 Tiger      300      1/1/1988   A3

FullTimeStudent
------------------
studentId, program

200        P1

studentdetail和fulltimestudent的studentid列引用student表的id列。
删除id=200的学生

delete t0, t2, t1 from StudentDetail t1
LEFT join FullTimeStudent t2 on (t1.studentId=t2.studentId) 
LEFT join Student t0 on (t1.studentId=t0.id) where t0.id=200;

错误：外键约束冲突。
如果将左连接更改为内连接，则删除成功。左连接有什么问题？
但左连接和内连接的选择没有区别。

select t0.id, t2.studentId, t1.studentId from StudentDetail t1
LEFT join FullTimeStudent t2 on (t1.studentId=t2.studentId) 
LEFT join Student t0 on (t1.studentId=t0.id) where t0.id=100;

返回一行。