可能在聲明中使用匿名類型成員嗎？

Question

好了，我試圖把這個：

sSelect = "SELECT CONVERT(VARCHAR, CommitDate, 101) AS XLabel, " + 
    "SUM(CASE WHEN NOT CompletionDate IS NULL THEN 1 ELSE 0 END) AS ClosedEvents, " + 
    "COUNT(CommitDate) AS Total, " + 
    "COUNT(CommitDate) - SUM(CASE WHEN NOT CompletionDate IS NULL THEN 1 ELSE 0 END) AS OpenEvents, " + 
    "SUM(CASE WHEN CompletionDate IS NULL AND commitdate < Convert(varchar(12),getdate(),101) THEN 1 ELSE 0 END) AS BehindSchedule"; 

到LINQ查詢。到目前爲止，我得到了：

var vEventsEntriesEnum = dtEventsEntries.AsEnumerable(); 

var vOpenEntriesData = from r in vEventsEntriesEnum 
select new 
{ 
    XLabel = r["CommitDate"], 
    ClosedEvents = vEventsEntriesEnum.Sum(closed => (closed["CompletionDate"] != null) ? 1 : 0), 
    Total = vEventsEntriesEnum.Count(total => (total["CommitDate"] != null) ? true : false), 
    OpenEvents = Total - ClosedEvents, 
}; 

這是我意識到我可能有問題。在這種情況下，Total和ClosedEvents不存在。

雖然我可以繼續前進，重複查詢ClosedEvents和Total和cast然後減去它們或任何東西，但我希望會有更好的方法。

如果還有其他的方式來處理我正在處理的其他代碼，請隨時通知我。

任何想法？

Answer 1

你必須在某個地方實現它。在查詢語法中，您可以使用以下代碼：let clause：

var vOpenEntriesData = from r in vEventsEntriesEnum 
    let ClosedEvents = vEventsEntriesEnum.Sum(closed => (closed["CompletionDate"] != null) ? 1 : 0) 
    select new 
    { 
     XLabel = r["CommitDate"], 
     ClosedEvents, 
     Total = vEventsEntriesEnum.Count(total => (total["CommitDate"] != null) ? true : false), 
     OpenEvents = Total - ClosedEvents, 
    }; 

這與循環中的變量類似。