集团由+所有在...？

Question

我想知道所有连接的值是否在另一个表中。

例子：

id childId 
1 2 
1 3 
1 4 
2 6 
2 7 
2 8 
2 9 

childIds 
2 
3 
4 
6 
7 



**desired result:** 

id allChildrenInChildIds 
1 True 
2 False 

什么是做到这一点的最好方法是什么？

Answer 1

SQL Fiddle DEMO

select id, case when sum(TrueorFalse) = count(1) then 'true' 
       else 'false' end 
from (
select id, case when exists (select 1 from ChildIDs where id = childid) then 1 
      else 0 
      end as TrueOrFalse 
from child) A 
group by A.id 

使用时存在（选择... ...从）

Answer 2

如果您运行此查询

SELECT id, GROUP_CONCAT(childId) 
FROM table 
WHERE childId NOT IN (2,3,4,5,6,7,8) 
GROUP BY id 

结果中的任何想法将是错误的。我添加了GROUP_CONCAT，因此您可以确定哪个childId不在集合中。如果一个id不在结果中，那么它是真的。

Answer 3

试试这个

SELECT 
    ID 
    ,MIN(allChildrenInChildIds) 
FROM 
(
    SELECT id, 
    CASE WHEN childId IN (SELECT childIds FROM Table2) THEN 'TRUE' ELSE 'FALSE' 
    END AS allChildrenInChildIds 
    FROM Table1 
) result 
GROUP BY ID 

Answer 4

像这样的事情？

select 
    id, 
    case when exists (
    select c.childid 
    from Child as c 
    where c.id = ids.id 
    and not exists (
     select * 
     from Childids 
     where c.childid = Childids.id 
    )) then 'No' else 'Yes' end as WereAllChildrenFound 
from ids 

Answer 5

这个怎么样？

select id , case when count(c.childid) <> count(ci.childid) then 'false' else 'true' end as allChildrenInChildIds 
from Child c 
left join ChildIds ci 
on c.childid = ci.childid 
group by id