Question

我有两个表：FEATURE和FEATURE_DETAILS。关系是一个（FEATURE）到多个（FEATURE_DETAILS）。

feature_details_id | feature_id
1                        1
1                        2
1                        4 
2                        1
2                        2
2                        4
2                        5
3                        1
3                        5

如何选择包含例如的所有行？ 5？

feature_details_id | feature_id
2                        1
2                        2
2                        4
2                        5
3                        1
3                        5

Answer 1

首先获取feature_id为5的feature_deatails_id列表，然后将feature_deatails_id传递给FEATURE_DETAILS表以获得结果

尝试这样的事情

select * 
from FEATURE_DETAILS 
where feature_deatails_id in(
                  select feature_deatails_id from FEATURE_DETAILS where feature_id = 5)

或使用Max()Over()窗口功能（首选方法）

select * from 
(
select max(case when feature_id = 5 then 1 else 0 end)over(partition by feature_deatails_id) as cnt,
       feature_deatails_id,feature_id 
from FEATURE_DETAILS 
)s
Where cnt = 1

Answer 2

SELECT * FROM FEATURE_DETAILS WHERE feature_details_id IN (
  SELECT feature_details_id from FEATURE_DETAILS WHERE feature_id=5
)

如果只匹配一个，则选择所有行

2 个答案: