SQL如何在自联接上查询

Question

一个sql问题让我很困惑，我有两个这样的表

create table faculty
(fac No
 fac first name
 fac last name
 fac supervisor No)

另一个是

create table offering
(offer No
 course No
 offterm
 offyear
 offlocation
 offime
 facNo   )

现在，我需要编写一个查询，其中列出了教职员工的姓名以及该教职员工在2010年与其主管一起教授同一门课程的课程编号。

我试着这样写一个查询

select fa.FacNo,fa.FacFirstName,fa.FacLastName
from faculty as fa,faculty as fs,Offering as o, Offering as os
where fa.FacSupervisor = fs.FacNo
and fa.FacNo = o.FacNo
and fa.FacSupervisor = os.FacNo
and o.OffYear = 2010

但我没有正确的答案，所以请给我一些提示

谢谢大家，我的工作如下

select f.FacFirstName,F.FacLastName,s.FacFirstName as SupFirstname,s.FacFirstName as        SupLasName,o.CourseNo
from faculty as f, Faculty as s ,Offering as o, Offering as os
where f.FacSupervisor = os.FacNo
and f.FacNo = o.FacNo
and o.CourseNo = os.CourseNo
and f.FacSupervisor = s.FacNo
and o.OffYear =2010 and os.OffYear =2010

我希望这对于一些面对相同问题的新SQL学习者有所帮助。

Answer 1

“所以请给我一些提示”

既然是您的问题，我很乐意提供提示。

使您的联接明确-极大地提高了可读性。 例如：

FROM faculty as fa
     INNER JOIN
     faculty as fs ON fa.FacSupervisor = fs.FacNo
     INNER JOIN
     Offering as o ON fa.FacNo = o.FacNo
     INNER JOIN
     Offering as os ON fs.FacNo = os.FacNo

一旦这样做，我怀疑您遇到任何问题都会好运。 或至少可以为我们提供更多帮助。

然后，您需要过滤

WHERE o.[course No] = os.[Course No]
  AND o.OffYear = 2010