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我在 LINQ 查询中对单个表进行多次计数时遇到问题。我正在使用 NHibernate、LINQ to NHibernate 和 C#。

查询是一个填充列表。我有一个表，它有一个名为 FullRef 的布尔值。我想做一个 LINQ 查询来计算每个 TrackId 上 FullRef = false 和 FullRef = true 的出现次数。每次获得 track.Source == "UserRef" 时，TrackId 都会获得一个新行。

在以下查询中，我得到了 FullRef = true 的正确数字计数（来自 FullRefTrueCount），但它在 FullRefFalseCount 上给出了一个未知的错误数字。

var query2 = from track in query
    where track.Source == "UserRef"
    group track by new { TrackId = track.TrackId, FullRef = track.FullRef } into d

    select new FullReferrer
    {
        Customer = d.Key.TrackId,
        FullRefFalseCount = d.Where(x => x.FullRef == false).Count(),
        FullRefTrueCount = d.Where(x => x.FullRef == true).Count()
    };

我还尝试将其修改为不包含 group by 中的 FullRef。这是通过像这样在 by 上删除 FullRef = track.FullRef 来完成的

var query2 = from track in query
    where track.Source == "UserRef"
    group track by new { TrackId = track.TrackId } into d

    select new FullReferrer
    {
        Customer = d.Key.TrackId,
        FullRefFalseCount = d.Where(x => x.FullRef == false).Count(),
        FullRefTrueCount = d.Where(x => x.FullRef == true).Count()
    };

现在它给了我 TrackId 的总数，忽略了我的 .Where(x => x.FullRef == true/false) 语句。

任何人都知道如何解决它？我想这是问题所在的“分组依据”。我可以以某种方式避免分组吗？我可能需要加入吗？

4

5 回答 5

3

对于 NHibernate 我不知道，但是使用带有实体框架的 Linq 这应该得到你想要的：

var query2 = (
    from track in someDbSet
    select new FullReferrer
    {
          Customer = track.trackId
        , FullRefFalseCount = (from fullRefFalse in someDbSet.tracks
                               where fullRefFalse.IsSale == false 
                               && fullRefFalse.trackId == track.trackId
                               select fullRefFalse).Count()
        , FullRefTrueCount = (from fullRefTrue in someDbSet.tracks
                              where fullRefTrue.IsSale == true
                              && fullRefTrue.trackId == track.trackId
                              select fullRefTrue).Count()
    }
).Distinct();
于 2013-06-07T12:10:45.333 回答
1 
FullRefFalseCount = d.Where(x => x.FullRef == false).ToList().Count
FullRefTrueCount = d.Where(x => x.FullRef == true).ToList().Count

尝试这个

于 2013-06-07T11:38:28.443 回答
0

试试计数（条件）。

    FullRefFalseCount = d.Count(x => x.FullRef == false),
    FullRefTrueCount = d.Count(x => x.FullRef == true)
于 2013-06-07T11:25:42.190 回答
0

尝试这个。这会从数据表中获取预期数据。

string source = "UserRef";
var result = from row in dt.AsEnumerable()
             where row["source"].Equals(source)
             group row by row["TrackId"]
             into g
             select new
                {
                   TrackId = g.Key,
                   FullRefTrueCount = ((from track in g where track["FullRef"].Equals("true") select track).Count()),
                   FullRefFalseCount = ((from track in g where track["FullRef"].Equals("false") select track).Count())
                };
于 2013-06-07T11:44:16.867 回答
0

对于其他有类似问题的人，我通过将其设置为“.AsEnumerable()”来解决它

var query2 = from track in query.AsEnumerable() // <--- the solution
    where track.Source == "UserRef"
    group track by new { TrackId = track.TrackId } into d

    select new FullReferrer
    {
        Customer = d.Key.TrackId,
        FullRefFalseCount = d.Count(x => !x.FullRef),
        FullRefTrueCount = d.Count(x => !x.FullRef)
    };
于 2013-06-13T11:15:30.377 回答