c# - 使用 Group by 的 Linq to SQL

Question

我正在尝试将此 T-SQL 转换为 Linq To SQL，但无法通过聚合函数计算出组。欢迎任何帮助。

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

Answer 1

要按复合键分组，您通常使用匿名类型:

    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) };