How to sum for a parent/child relationship in MS Access
问题 I have a number of Matters which are in a parent/child relationship. Each has a pointer to their parent matter, or null if they are the parent. Each matter can have a payment made, but all payments in a parent/child relationship are shared between both parent and child. A simplified version of my tables is: Matter | ID | Value | ParentID | -------------------------------------- | 1 | 200 | 0 | | 2 | 200 | 1 | | 3 | 300 | 0 | | 4 | 200 | 1 | | 5 | 800 | 0 | Payment | ID | Value | MatterID | --