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 | -------------------------------------- | 1 | 100 | 1 | | 2 | 50 | 4 | | 3 | 20 | 3 |
Note that Matter values are inherited by children (in reality it's just a reference)
I would like to query:
- The remaining amount on every matter = ([Value] - Sum([All Payments in Parent/Child Relationship))
- A view of all parent matters, which incorporates the sum of all payments in parent/child relationship.
I am thinking of having a join query showing for each Payment which ParentMatter they apply to, but that will not help me when looking from the child view?
The expected results are:
1. Query only parent matters | ID | Value | TotalRcvd | -------------------------------------- | 1 | 200 | 150 | | 3 | 300 | 20 | | 5 | 800 | 0 | 2. Query all matters | ID | Value | TotalRcvd | -------------------------------------- | 1 | 200 | 150 | | 2 | 200 | 150 | | 3 | 300 | 20 | | 4 | 200 | 150 | | 5 | 800 | 0 |
Where [TotalRcvd] is the sum of all payments that appply to that matter. For example, matter 1 is the parent matter of matters 2 and 4 (ParentID reference in Matter table). Any payments recorded against matters 1, 2 or 4 will go towards the TotalRcvd for each of them. Therefore they each have a total received [TotalRcvd] of 150.
Any help appreciated.
来源：https://stackoverflow.com/questions/29958047/how-to-sum-for-a-parent-child-relationship-in-ms-access