显示学生，其中两名学生喜欢对方在SQL

Question

我有其中您可以查看这里的样本数据库的列表：https://class.stanford.edu/c4x/Engineering/db/asset/socialdata.html

，我试图写，做以下的SQL语句：显示一个列表的学生，两个学生都喜欢对方。

这是我的代码：

SELECT A.name, B.name, C.name, D.name 
FROM Highschooler A, Highschooler B, Highschooler C, Highschooler D, Likes L 
WHERE A.ID = L.ID1 AND B.ID = L.ID2 AND C.ID = L.ID2 AND D.ID = L.ID1 AND A.name < B.name AND D.name < C.name 
ORDER BY A.name, B.name, C.name, D.name ASC; 

我不知道它是否显示正确的，这是我所得到的：

Alexis  Kris  Kris  Alexis 
Andrew  Cassandra Cassandra Andrew 
Austin  Jordan  Jordan  Austin 
Brittany Kris  Kris  Brittany 
Cassandra Gabriel  Gabriel  Cassandra 
Jessica  Kyle  Kyle  Jessica 

Answer 1

我要说的是，你正在寻找的是一样的东西：

select A.name || ' likes ' || B.name 
from Highschooler A 
join likes   on A.id = Likes.ID1 
join Highschooler B on B.id = Likes.ID2