sql - 从 3 个一对一关系表 (Oracle) 中检索值

Question

每个Student都有Teacher自己的UNIQUE UserID
是否可以一次从三个表中检索值？这样：它将显示UserID每个人拥有的Student或Teacher？我尝试了以下查询，但它不起作用：

SELECT u.UserID, StudentID, TeacherID  
FROM User u  
INNER JOIN (SELECT * FROM Student, Teacher) ss  
ON u.UserID = ss.UserID  

Answer 1

也许这样：

SELECT u.UserID, S.StudentID, T.TeacherID  
from User U
left join Student S on S.UserID = u.UserID  
left join Teacher T on T.UserID = U.UserID