PostgreSQL - 消除类似行，但仅限于某些值

Question

我们说我有一个包含三列的表 - 身份证，姓名和性别。可能有多个具有相同名称的ID。可能还有多个同名的性别。

对于除了一个名字以外的所有名字，我完全可以，因为女性和男性都有一排，而对于双性人则有一排，依此类推。然而，对于丹尼尔和唯一的丹尼尔，我不能允许那里有男性排和女性排（尽管双性人等完全没问题）。如果男性和女性排都有丹尼尔的名字，我想排除男性排，只留下女排和其他任何性别。

id | name   | gender
---+--------+---------
1  | Andrew | male
1  | Andrew | female
2  | Andrew | female
1  | Megan  | male
1  | Megan  | female
1  | Megan  | intersex
2  | Megan  | male
2  | Megan  | female
4  | Megan  | intersex
1  | Daniel | male      -- this row must be eliminated...
1  | Daniel | female    -- beacuse this row is present.
1  | Daniel | intersex  -- But this one is totally cool.
1  | Daniel | porcupine -- So is this one.
2  | Daniel | male      -- this row must be eliminated...
2  | Daniel | female    -- beacuse this row is present.
3  | Daniel | male      -- But this row is totally cool, 
                        -- because there's no female Daniel row
                        -- with an id of 3.

如何删除这些行？我有一种潜在的怀疑，我错过了一些非常明显的东西......

Answer 1

这应该这样做：

DELETE FROM tablename t WHERE name='Daniel' AND gender='male'
  AND EXISTS (SELECT 1 FROM tablename
              WHERE name='Daniel' AND id=t.id AND gender='female');