sql - 关系代数

Question

你能帮我用关系代数解决这个问题吗？我有这个 DB(论文答辩)；

• 教师(Teacher_ID、姓名、专业)
• 项目(Project_ID、职位、专业)
• 论文(Thesis_ID、Project_ID、Jury_ID、Decision)
• 陪审团(Jury_ID、主管_ID、First_Member_ID、Second_Member_ID)

我想找到代数查询来获得指导他们专业论文的教师(ID，姓名)；

我已经用 SQL 完成了，它应该是这样的:

Select Teacher_ID, Name  
From Teachers T  
Where Teacher_ID IN
      (Select Supervisor_ID  
       From Juries  
       Where Jury_ID IN
             (Select Jury_ID  
              From Thesis  
              Where Project_ID IN 
                    (Select Project_ID  
                     From Projects P  
                     Where T.Specialty = P.Specialty)))  

感谢您的帮助!

Answer 1

你要这样做吗？

select Te.Teacher_ID,Te.Name from thesis t
join project P on (T.Speciality =P.Speciality)
join Juries J on ( J.jury_ID = T.Jury_id)
join Teacher Te on (Te.Teacher_ID = J.Supervisor_ID)