如果只有一个匹配，请选择所有行

Question

我有两个表格：FEATURE和FEATURE_DETAILS。关系是一个（FEATURE）与许多（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 

如何选择所有包含例如5？

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

Answer 1

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

Answer 2

首先得到feature_deatails_id针对FEATURE_ID是5的列表，然后通过feature_deatails_id到FEATURE_DETAILS表得到的结果

尝试是这样的

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