JOIN of 2 tables where cross all records

Question

Given these 2 tables

Table name: MyValues

Id	IdValue
1	10
2	10
3	10
1	11

Table name: MyConditions

Id	IdValue
7	10
7	11

How could I write a query to get the Ids from the MyValues table to return the ones that match all the records on MyConditions table where MyValues.IdValue = MyConditions.IdValue

So the result would be 1 (since Id 1 from MyValues table matches all records in MyConditions table)

Answer 1

This reads like a relational division problem. We can join, and filter with having:

select v.id
from myvalues v
inner join myconditions c on c.idvalue = v.idvalue
group by v.id
having count(*) = (select count(*) from myconditions)

This assumes no duplicate (id, idvalue) in myvalue, and no duplicate idvalue in mycondition. Otherwise, we would typically use distinct on one or both side of having:

having count(distinct v.idvalue) = (select count(distinct idvalue) from myconditions)