SQL：从谓词逻辑到SQL SELECT

Question

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)))

我进一步翻译为：

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

用作'formulas'：

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

考虑到开头错误的概率，这里是开头的表述：

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

Knows 和 Likes table 不是对称的，只包含 Person table 的外键，因此表示 Person X Knows/Likes Person Y.

对于上述情况，SQL SELECT 查询会是什么样子？

我已经试过了但是没有用：

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))

Answer 1

查找认识但不喜欢的人的列表。然后 select 来自不在那个集合中的人。

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
   )

SQL：从谓词逻辑到SQL SELECT

SQL: from predicate logic to SQL SELECT

sql

predicate