子總計關係的數據表

Question

我有一個數據表與關係數據結構，我需要總結子節點到它們的父節點的所有一直到

我已附加2個圖像的頂部父（NULL父ID）這表明原始表和其他與預期結果

乾杯

Answer 1

我已經採取了一種模擬數據的方法，因爲它們可能已經通過某些ORM實現了數據庫，即包含數據和子集合的類。再加上一些「商業邏輯」來計算所需的數字。所以你可以選擇一種數據庫方式以及內存方式。

在Linqpad：

void Main() 
{ 
    var data = new[] 
    { 
     new Record { Id = 1, ParentId = null, Qty = 1, Cost = 0.0m }, 
     new Record { Id = 2, ParentId = 1, Qty = 2, Cost = 0.0m }, 
     new Record { Id = 3, ParentId = 1, Qty = 3, Cost = 0.0m }, 
     new Record { Id = 4, ParentId = 2, Qty = 4, Cost = 0.0m }, 
     new Record { Id = 5, ParentId = 3, Qty = 5, Cost = 0.0m }, 
     new Record { Id = 6, ParentId = 2, Qty = 6, Cost = 1.7m }, 
     new Record { Id = 7, ParentId = 4, Qty = 7, Cost = 1.8m }, 
     new Record { Id = 8, ParentId = 5, Qty = 8, Cost = 1.9m }, 
     new Record { Id = 9, ParentId = 5, Qty = 9, Cost = 2.0m }, 
    }.ToList(); 

    // Mimic ORM's job: 
    data.ForEach(d => d.ChildRecords = 
     data.Where(c => c.ParentId == d.Id).ToList()); 

    data.Select(d => new { d.Id, d.Cost, d.TotalCost }).Dump(); 
} 

class Record 
{ 
    public int Id { get; set; } 
    public int? ParentId { get; set; } 
    public int Qty { get; set; } 

    private decimal _cost = 0m; 
    public decimal Cost 
    { 
     get { return this._cost + this.ChildRecords.Sum(cr => cr.TotalCost); } 
     set { this._cost = value; } 
    } 

    public decimal TotalCost 
    { 
     get { return this.Qty * this.Cost; } 
    } 

    public ICollection<Record> ChildRecords; 
} 

結果：

Id Cost TotalCost 
1 619.2 619.2 
2 60.6 121.2 
3 166  498 
4 12.6 50.4 
5 33.2 166 
6 1.7  10.2 
7 1.8  12.6 
8 1.9  15.2 
9 2  18 

的優化可以應用一些記憶化，即讓成本屬性存儲在它的私有成員變量的getter的結果。