sql - SQL:从谓词逻辑到SQL SELECT

我正在尝试了解如何有效地将谓词逻辑转换为SQL查询。我被困在：

For all P(x), (for all P(y), (Knows(x,y) -> Likes(x,y)))

我进一步将其翻译为：

-exists P(x), (exists P(y), (Knows(x,y) /\ -Likes(x,y)))

用作“公式”：

for all x, (A -> B) <=> -exists x, (A /\ -B); for all x, (A) <=> -exists x, (-A)

出现错误的机率如下：

Write a query that returns the name of all persons that like everyone they know.

其中Knows和Likes表不是对称的，仅包含Person表的外键，因此表达Person X Knows / Like PersonY。

上面的SQL SELECT查询的外观如何？

我已经尝试过了，但是没有用：

SELECT P.name
FROM Persons P
WHERE NOT EXISTS (
    SELECT *
    FROM Knows K
    WHERE K.personB_id NOT IN (
        SELECT L.personB_id
        FROM Likes L
        WHERE K.personA_id = L.personA_id
        AND K.personB_id <> L.personB_id))

最佳答案

查找认识自己不喜欢的人的人的名单。然后从不在该集合中的人中选择。

SELECT FROM Persons
    WHERE Persons.ID NOT IN (
        SELECT Knows.PersonA
        FROM Knows LEFT JOIN Likes
        ON Knows.PersonA = Likes.PersonA
        AND Knows.PersonB = Likes.PersonB
        WHERE Likes.PersonB is null
   )