在SQL中选择包含所有子项的父记录

依赖于数字技巧(父子链接的数量=子节点数,父节点链接到所有子节点):

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 
)