LINQ到用SQL集团 [英] Linq to SQL with Group by

问题描述

我想这个T-SQL转换为LINQ to SQL的，但不能用聚合函数制定出组。任何帮助的欢迎。

 选择c.ClientID，给定名称，姓氏，MAX（a.Address），MAX（t.Value）从客户端C 
 
留在c.ClientID = a.ClientID 
加入ClientAddress一个向左c.ClientID，给定名称上c.ClientID = t.ClientID 
组的加入ClientContactŤ ，姓
  

解决方案

要组一个复合键，通常使用匿名类型：

  VAR QRY =由新{x.ClientID在someSource 
组X X，X .GivenName，x.Surname}到GRP 
选择新的{grp.Key，地址= grp.Max（X => x.Address），
值= grp.Max（X => X .value的）}; 
  

I am trying to convert this T-SQL to a Linq To SQL but can't work out the group by aggregate functions. Any help welcome.

select c.ClientID, GivenName, Surname, max(a.Address), max(t.Value)
from Client c
left join ClientAddress a on c.ClientID = a.ClientID
left join ClientContact t on c.ClientID = t.ClientID
group by c.ClientID, GivenName, Surname

解决方案

To group by a composite key, you typically use an anonymous type:

    var qry = from x in someSource
              group x by new { x.ClientID, x.GivenName, x.Surname } into grp
              select new { grp.Key, Address = grp.Max(x => x.Address),
                  Value = grp.Max(x => x.Value) };

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