Select Parent Record With All Children in SQL - sql

Question

Let's say I have two tables, "Parent" and "Child". Parent-to-Child is a many:many relationship, implemented through a standard cross-referencing table.
I want to find all records of Parent that are referenced by ALL members of a given set of Child using SQL (in particular MS SQL Server's T-SQL; 2005 syntax is acceptable).
For example let's say I have:
List item
Parent Alice
Parent Bob
Child Charlie references Alice, Bob
Child David references Alice
Child Eve references Bob
My goals are:
If I have Children Charlie, I want the result set to include Alice and Bob
If I have Children Charlie and David, I want the result set to include Alice and NOT Bob.
If I have Children Charlie, David, and Eve, I want the result set to include nobody.

Answer 1

Relying on a numerical trick (where the number of parent-child links = the number of children, that parent is linked to all children):
SELECT Parent.ParentID, COUNT(*)
FROM Parent
INNER JOIN ChildParent
ON ChildParent.ParentID = Parent.ParentID
INNER JOIN Child
ON ChildParent.ChildID = Child.ChildID
WHERE <ChildFilterCriteria>
GROUP BY Parent.ParentID
HAVING COUNT(*) = (
SELECT COUNT(Child.ChildID)
FROM Child WHERE <ChildFilterCriteria>
)

Answer 2

Here's an answer.
SQL query: Simulating an "AND" over several rows instead of sub-querying
And here's a specific application of that to this problem.
SELECT * FROM Parents
WHERE ParentId in
(
SELECT ParentId FROM ChildParent
WHERE ChildId in
(
SELECT ChildId FROM Child
WHERE ChildName in ('Charlie', 'David')
)
GROUP BY ParentId
HAVING COUNT(*) = 2
)

Answer 3

( I guess where you said "Child Eve references Eve" you meant "Child Eve references Bob", right?)
I think I've got it... looks ugly... the secret is the double negation... that is, everyone for which it's true,, is the same as not anyone for which is false... (ok, I have troubles with my english, but I guess you understand what I mean)
select * from parent
parent_id name
--------------------------------------- --------------------------------------------------
1 alice
2 bob
select * from child
child_id name
--------------------------------------- --------------------------------------------------
1 charlie
2 david
3 eve
select * from parent_child
parent_id child_id
--------------------------------------- ---------------------------------------
1 1
2 1
1 2
2 3
select * from parent p
where not exists(
select * from child c
where
c.child_id in ( 1, 2, 3 ) and
not exists(
select * from parent_child pc where
pc.child_id = c.child_id and
pc.parent_id = p.parent_id
)
)
--when child list = ( 1 )
parent_id name
--------------------------------------- --------------------------------------------------
1 alice
2 bob
--when child list = ( 1, 2 )
parent_id name
--------------------------------------- --------------------------------------------------
1 alice
--when child list = ( 1, 2, 3 )
parent_id name
--------------------------------------- --------------------------------------------------
well, I hope it helps...