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我还在学习linq，现在我很困惑。我需要来自 3 个表的报告数据，我得到了结果，但它是重复的。我使用了 distinct 但它不起作用，n 我需要数据总和仍然不起作用。

这是我的桌子

TBL_MKN_MNM                               TBL_DETAIL                 TBL_TRANSACTION 

ID_A  Name        Price   Stock       ID_B  ID_A ID_C  MANY     ID_C   DATE      PAY   
11   pepsi       2500     15          1     11   1234  1        1234   2013-05-22  6000
22   coca-cola   3000     16          2     22   1234  1        6666   2013-05-22  10000
                                      3     11   6666  2          
                                      4     22   6666  1


the result I want
Name        MANY   PRICE   AMOUNT  LeftStock
Pepsi        3     2500    7500     12
Coca-Cola    2     3000    6000     14 

Total 13500

这是我的查询，有人可以解释什么是错的吗？ 

var report= (from u in myDb.TBL_TRANSAKSI_MKN_MNMs.AsEnumerable()
  where u.TGL_TRANSAKSI.Value.Date.Equals(dateTimePicker1.Value.Date)
  join l in myDb.TBL_DETAIL_TRANSAKSIs.AsEnumerable() on u.ID_NOTA equals l.ID_NOTA
  join m in myDb.TBL_MKN_MNMs.AsEnumerable() on l.ID_MKN_MNM equals m.ID_MKN_MNM
  group new { u, l, m } by new { m.NAMA_MKN_MNM, m.HARGA_JUAL, u.TGL_TRANSAKSI, l.ID_MKN_MNM, u.USERNAME, l.Jumlah }
  into grp                 
  select new 
  {                         
      MakanMinum = grp.Key.NAMA_MKN_MNM,
      HargaJual = grp.Key.HARGA_JUAL,
      Stok = grp.Sum(groupedthing => groupedthing.l.Jumlah), 
      Tanggal =  grp.Key.TGL_TRANSAKSI,
      Jumlah =(grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)),
      Total = grp.Sum(grouptotal => grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)),
      Username = grp.Key.USERNAME
  }).Distinct();
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1 回答 1

1

第一：你不应该使用匿名类作为你的查询结果。

第二：你应该使用Enumerable.Distinct<TSource> Method (IEnumerable<TSource>, IEqualityComparer<TSource>)而不是当前 Enumerable.Distinct<TSource> Method (IEnumerable<TSource>)

见链接：

http://msdn.microsoft.com/en-us/library/bb338049.aspx

这是我的建议：

var report= (from u in myDb.TBL_TRANSAKSI_MKN_MNMs.AsEnumerable()
  where u.TGL_TRANSAKSI.Value.Date.Equals(dateTimePicker1.Value.Date)
  join l in myDb.TBL_DETAIL_TRANSAKSIs.AsEnumerable() on u.ID_NOTA equals l.ID_NOTA
  join m in myDb.TBL_MKN_MNMs.AsEnumerable() on l.ID_MKN_MNM equals m.ID_MKN_MNM
  group new { u, l, m } by new { m.NAMA_MKN_MNM, m.HARGA_JUAL, u.TGL_TRANSAKSI, l.ID_MKN_MNM, u.USERNAME, l.Jumlah }
  into grp                 
  select new MyClass
  {                         
      MakanMinum = grp.Key.NAMA_MKN_MNM,
      HargaJual = grp.Key.HARGA_JUAL,
      Stok = grp.Sum(x=>x.l.Jumlah),  
      Tanggal =  grp.Key.TGL_TRANSAKSI,
      Jumlah =(grp.Key.HARGA_JUAL *  grp.Sum(x=>x.l.Jumlah)),
      Total = grp.Sum(grouptotal => grp.Key.HARGA_JUAL *  grp.Sum(x=>x.l.Jumlah)),
      Username = grp.Key.USERNAME
  }).Distinct(new MyClassComparer());


class MyClass
{
  public int MakanMinum {get;set;}
  pubic int HargaJual {get;set;}
  ...
}



class MyClassComparer : IEqualityComparer<MyClass>
{

    public bool Equals(MyClass x, MyClass y)
    {

        if (Object.ReferenceEquals(x, y)) return true;


        if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
            return false;


        return x.MakanMinum  == y.MakanMinum  && x.HargaJual= y.HargaJual;
    }

    public int GetHashCode(MyClass m)
    {

        if (Object.ReferenceEquals(m, null)) return 0;

        return m.MakanMinum.GetHashCode()^ m.HargaJual.GetHashCode();
    }

}
于 2013-06-30T04:20:06.470 回答