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Linq到SQL:与匿名类型不同

anonymous-types distinct linq-to-sql

1

tsilb · 技术社区 · 17 年前

dgIPs.DataSource = 
    from act in Master.dc.Activities
    where act.Session.UID == Master.u.ID
    select new
    {
      Address = act.Session.IP.Address,
      Domain = act.Session.IP.Domain,
      FirstAccess = act.Session.IP.FirstAccess,
      LastAccess = act.Session.IP.LastAccess,
      IsSpider = act.Session.IP.isSpider,
      NumberProblems = act.Session.IP.NumProblems,
      NumberSessions = act.Session.IP.Sessions.Count()
    };

如何仅基于Distinct地址提取Distinct()?也就是说,如果我简单地添加Distinct(),它会将整行计算为Distinct,因此无法找到任何重复项。我想为每个act.Session.IP对象只返回一行。

this answer ,但情况似乎有所不同。另外,如果我只选择act.Session.IP,Distinct()也可以正常工作,但它有一个我希望避免检索的列,我不希望通过手动绑定我的datagrid列来实现这一点。

2 回复 | 直到 9 年前

1

3

eglasius 17 年前

dgIPs.DataSource = 
    from act in Master.dc.Activities
    where act.Session.UID == Master.u.ID
    group act by act.Session.IP.Address into g
    let ip = g.First().Session.IP
    select new
    {
      Address = ip.Address,
      Domain = ip.Domain,
      FirstAccess = ip.FirstAccess,
      LastAccess = ip.LastAccess,
      IsSpider = ip.isSpider,
      NumberProblems = ip.NumProblems,
      NumberSessions = ip.Sessions.Count()
    };

或:

dgIPs.DataSource = 
    from act in Master.dc.Activities
    where act.Session.UID == Master.u.ID
    group act.Session.IP by act.Session.IP.Address into g
    let ip = g.First()
    select new
    {
      Address = ip.Address,
      Domain = ip.Domain,
      FirstAccess = ip.FirstAccess,
      LastAccess = ip.LastAccess,
      IsSpider = ip.isSpider,
      NumberProblems = ip.NumProblems,
      NumberSessions = ip.Sessions.Count()
    };

2

0

John Saunders 17 年前

Enumerable.Distinct的重载之一接受IEqualityComparer实例。只需编写一个实现IEqualityComparer的类,该类只比较两个地址属性。

不幸的是,您必须为正在使用的匿名类命名。