mysql - 如何从同一列表中选择包含 ID 而不是仅包含 ID 的记录

Question

我希望选择的记录包含选定的 ID，但不只包含来自同一列表的这些 ID。

我的 SQL 代码:

select question_id, person_id from `answers` where
`person_id` in ('9', '18')

结果:

2, 9
2, 18
4, 9
4, 18
5, 18
6, 9

预期结果:

5, 18
6, 9

完整的 SQL 查询:

select id, name
from questions
where id not in ('3', '13') and
exists (select `id` from `answers` where `answers`.`question_id` = `questions`.`id`
and `person_id` in ('9', '18')) order by RAND() limit 1

Answer 1

你可以尝试使用 group by 和 having

select question_id, person_id 
from `answers` 
where person_id` in ('9', '18')
group by question_id 
having count(distinct person_id) =  1

仅选择集合中具有 person_id 但仅匹配一个值的行