Select Parent Record With All Children in 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 fi

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 
GROUP BY Parent.ParentID
HAVING COUNT(*) = (
    SELECT COUNT(Child.ChildID)
    FROM Child WHERE 
)