LINQ採用語法

Question

我寫了一些LINQ來模擬SQL GroupBy語句（請參見下文）。不過，在做羣組之前，我也只需要考慮最後的10個設置ID。我想我會用Take來做到這一點，但是在我的陳述中，正確的語法是什麼？

var settings2 = from s in dc.SystemSettings 
       where s.campConfig.campaignType == campType 
         && s.campId != campId 
         && s.settingKey == ticket.setting.Key 
       orderby s.settingId descending 
       group s by s.settingValue 
       into grp 
       select new 
       { 
        SettingValue = grp.Key, 
        SettingCount = grp.Select(x => x.settingValue).Count() 
       }; 

Answer 1

我會做這樣的事情

var settings2 = from sOuter in 
    (from s in dc.SystemSettings 
    where s.campConfig.campaignType == campType 
     && s.campId != campId 
     && s.settingKey == ticket.setting.Key 
    orderby s.settingId descending 
    select s).Take(10) 
    group sOuter by sOuter.settingValue 
    into grp 
    select new 
    { 
     SettingValue = grp.Key, 
     SettingCount = grp.Select(x => x.settingValue).Count() 
    };