垿娃子：感谢题主的分享 第二个题目用题目中的案例测试了一下是正确的，如有错误还请大家指正 CREATE VIEW people AS SELECT p1 as p from friends UNION SELECT p2 from friends; -- 所有的人的集合 CREATE VIEW relation AS SELECT p1, p2 FROM friends UNION SELECT p2, p1 FROM friends -- 所有的关系 SELECT people.p as p1, r2.p2 as p2 FROM people, relation r1, relation r2 WHERE r1.p2 = r2.p1 AND people.p = r1.p1 AND people.p <> r2.p2 -- 得到所有从第一个人到第三个人的关系 AND NOT EXISTS (SELECT * FROM relation r3 WHERE r3.p1 = people.p AND r3.p2 = r2.p2) -- 用关联子查询筛选掉第一个人与第二个人认识的行 AND people.p < r2.p2 -- 筛选掉重复的关系