我已经玩了一段时间,但是无法得到它.我是Linq,C#和这些Lambda的新手. 我想要做的是根据每个实体的两个属性对实体进行分组.这是一个消息实体：Message { int UserId; //The user generating the message int UserIdTo; //The receiver of the message |...| // Other stuff }所以,我想要它,以便这些UserId = 5,UserIdTo = 6和UserId = 6,UserIdTo = 5将在同一组中. 这是我的开始：var groupList = (from m in db.Messageswhere m.U...
我有物品的物品：public int ClientId {get;set;} public DateTime StartDateTime{get;set;} public DateTime EndDateTime{get;set;}我想计算每个客户端与group by的所有日期时间之间的差异总和,但是这样：var retVal = (from t items group t by ClientId into z select new{ClientId = z.Key,TimeSpanClientTotal = z.Sum(h => (h.EndDateTime - h.StartDateTime))}).ToList();由于Sum不能很好地用于TimeSpan,这是两个Date...
我有代码,我按机会号码分组我的要求,如下所示：List<Requirement> result = requirements.GroupBy(l => l.CRMOpportunityNumber).Select(cl => new Requirement{CRMOpportunityNumber = cl.First().CRMOpportunityNumber,OpportunityTitle = cl.First().OpportunityTitle,ClientName = cl.First().ClientName,TentativeStartDate = cl.Min(c => c.TentativeStartDate),TotalPositions = cl.Sum(c => c.Required),RegionName = cl.F...
我尝试将datatable转换为特殊格式的JSON DataTable中的数据如下col1 col2 col3 col4 ---------------------A B c D1A B c D2A B c D3尝试将其转换为对象数组class obj {var col1;var col2;var col3;list<string> col4; }我尝试使用linq,但有点卡住了.var result = from row in dt.AsEnumerable()group row by new{c1 = row["col1"],c2 = row["col2"],c3 = row["col3"]}into sectionselect new{item = s...
我有一个类似于以下格式的表：id | name | year | Quality| Location | ------------------------------------------ 1 | Apple | year1 | Good | Asia | 2 | Apple | year2 | Better | Asia | 3 | Apple | year3 | Best | Asia | 4 | Apple | year1 | Best | Africa | 5 | Apple | year2 | Bad | Africa | 6 | Apple | year3 | Better | Africa | 7 | Apple | year1 ...
RowNum IMAGEID SCANEDATE COUNT 1 10000131 2012-07-04 00:00:00.000 1 2 10002626 2012-08-03 00:00:00.000 1 3 10003348 2012-09-06 00:00:00.000 1 4 10003589 2012-09-15 00:00:00.000 8 5 10003590 2012-05-15 00:00:00.000 8 6 10003591 2012-04-15 00:00:00.000 8 7 10003592 2012-03-15 00:00:00.000 8 8 10003595 2012-02-1...
概观 当我上课时public class RequestEntry {public int RequestId{get;set;}public string ApproverUserId{get;set;}public string ApproverUserName{get;set;}public DateTime RequestedDate{get;set;} }它包含在列表中：List<RequestEntry> RequestEntries = new List<RequestEntry>() {new RequestEntry{RequestId = 1, RequestedDate = new DateTime(2018,06,01), ApproverUserId = "STEVES", ApproverUserName = "Steve Smit...
原文:C# WPF DataGrid 分组（Group）效果如图，每个列的名字可以自定义。我随便用了”File”和”Attachment Name”。 在Window的Resources里面设置Style, GroupHeaderStyle：<Style x:Key="GroupHeaderStyle" TargetType="{x:Type GroupItem}"><Setter Property="Template"><Setter.Value><ControlTemplate TargetType="{x:Type GroupItem}"><Expander IsExpanded="True"><Expander.Header><TextBlock Text="{Binding Path=Name}"...
我在我的Web应用程序中使用MongoDB C#驱动程序2.4.4.我需要将文档分组到一个动态过滤它们的集合中.var query = collection.Aggregate().Match(y => y.IdLower.Contains(id)).Match(y => y.NameLower.Contains(name)).Group(key => key.Id,g => new {Id = g.Key}).ToList(); 我需要根据用户输入添加或删除匹配运算符,但我无法弄清楚如何. 我试过这样的事情：var query = collection.Aggregate();if(!string.IsNullOrWhiteSpace(id))...
Group By/Having操作符 适用场景：分组数据，为我们查找数据缩小范围。 说明：分配并返回对传入参数进行分组操作后的可枚举对象。分组；延迟 1.简单形式：var q =from p in db.Productsgroup p by p.CategoryID into gselect g;语句描述：使用Group By按CategoryID划分产品。 说明：from p in db.Products 表示从表中将产品对象取出来。group p by p.CategoryID into g表示对p按CategoryID字段归类。其结果命名为g，一旦重新命名，...