Question

我正在尝试用C＃重写一个旧的vb.net应用程序。我遇到了我需要转换的linq代码：

 (From wn In dtx.WebQueryGroupNames Group Join _
                    wqg In dtx.WebQueryGroups On wn.QueryGroupNameKey Equals wqg.QueryGroupNameKey _
                    Into Group _
                    From p In Group.DefaultIfEmpty() _
                    Select wn _
                    Where Not (From x In dtx.WebQueryGroups Where x.QueryKey = queryKey Select x.QueryGroupNameKey).Contains(wn.QueryGroupNameKey)).Distinct.ToList

到目前为止我所拥有的是：

 (from wn in dtx.WebQueryGroupNames Group join  
        wqg in dtx.WebQueryGroups on wn.QueryGroupNameKey equals wqg.QueryGroupNameKey 
        Into Group 
        from p in Group.DefaultIfEmpty() 
        select wn 
        where !(from x in dtx.WebQueryGroups where x.QueryKey = queryKey select x.QueryGroupNameKey).Contains(wn.QueryGroupNameKey)).Distinct();

我似乎无法找到有关Group和Into关键字的任何信息，因为它转换为C＃。我想我错过了一个关键点，使这个查询有意义。

Answer 1

我相信Group Join会转换为带有join子句的计划into。试试这个

 (from wn in dtx.WebQueryGroupNames join  
        wqg in dtx.WebQueryGroups on wn.QueryGroupNameKey equals wqg.QueryGroupNameKey 
        into g
        from p in g.DefaultIfEmpty() 
        select wn 
        where !(from x in dtx.WebQueryGroups where x.QueryKey = queryKey select x.QueryGroupNameKey).Contains(wn.QueryGroupNameKey)).Distinct();

请参阅http://msdn.microsoft.com/en-us/library/bb397905.aspx

Answer 2

您正在寻找的术语是Group By。

var queryLastNames =
    from student in students
    group student by student.LastName into newGroup
    orderby newGroup.Key
    select newGroup;

什么是C＃Linq相当于VB.Net Linq Group Join和Into关键字？

2 个答案: