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単純なLINQクエリを添付しています。以下のLINQクエリで説明されているように、これら3つのフィールド（Field1、Field2、Field3）をプルするより良い効率的な方法があるかどうかを調べたいと思います。

from currentCons in ActiveConnections
join accounts in Accounts on currentCons.New_AccountId equals accounts.AccountId                                     
let Field1 =(from holder in MapHolders
        join entity in Entities on stringmap.ObjectTypeCode equals   entity.ObjectTypeCode
        where entity.Name == "New_Connection"
        where holder.AttributeName == "New_Data"
        where holder.AttributeValue ==  currentCons.New_DATA_Val
        select holder.Value)
 let Field2=(from holder in MapHolders
        join entity in Entities on stringmap.ObjectTypeCode equals entity.ObjectTypeCode
        where entity.Name == "New_Connection"
        where holder.AttributeName == "New_Type"
        where holder.AttributeValue == currentCons.New_Type
        select holder.Value)
let Field3=(from holder in MapHolders
        join entity in Entities on stringmap.ObjectTypeCode equals entity.ObjectTypeCode
        where entity.Name == "New_Connection"
        where holder.AttributeName == "New_EntryPoint"
        where holder.AttributeValue == currentCons.New_EntryPoint
        select holder.Value)
   where currentCons.ModifiedOn >= Convert.ToDateTime("1/1/2011")
   where currentCons.ModifiedOn <= Convert.ToDateTime("5/5/2012")
   select new 
   {
      conId = currentCons.ConnectionId,
      ConName = currentCons.name,
      TypeId = currentCons.Type,
      AccountId = currentCons.AccountId,
      OId = currentCons.OwnerId,
      BandwidthId = currentCons.Bandwidth,
      EntryPointId = currentCons.EntryPoint,
      Cap = Field1 ,
      Dir=Field2,
      EP=Field3,
      ModifiedOn = currentCons.ModifiedOn
    }

もう1つの方法は、選択ブロックに直接配置することです。これを行うための効率的な方法は何ですか？

どんなポインタでも大歓迎です。

ありがとう。

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1 に答える 1

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var fromDate =  new DateTime(2011,1,1);
var toDatePlusOneDay = new DateTime(2012,5,5).AddDays(1); // add one day to ensure 

var result = from currentCons in ActiveConnections
            join accounts in Accounts on currentCons.New_AccountId equals accounts.AccountId                                     
            where currentCons.ModifiedOn >= fromDate
            where currentCons.ModifiedOn < toDatePlusOneDay 
            from holder in MapHolders
            where (holder.AttributeName == "New_Data" && holder.AttributeValue == currentCons.New_DATA_Val) || (holder.AttributeName == "New_Type" && holder.AttributeValue == currentCons.New_Type) || (holder.AttributeName == "New_EntryPoint" && holder.AttributeValue == currentCons.New_EntryPoint)
            select new 
            {
              conId = currentCons.ConnectionId,
              ConName = currentCons.name,
              TypeId = currentCons.Type,
              AccountId = currentCons.AccountId,
              OId = currentCons.OwnerId,
              BandwidthId = currentCons.Bandwidth,
              EntryPointId = currentCons.EntryPoint,
              ModifiedOn = currentCons.ModifiedOn,
              Cap = (holder.AttributeValue == currentCons.New_DATA_Val) ? holder.Value : null,
              Dir = (holder.AttributeValue == currentCons.New_Type) ? holder.Value : null,
              EP = (holder.AttributeValue == currentCons.New_EntryPoint) ? holder.Value : null              
            }

結果に使用されていないため、以下を削除しました

join entity in Entities on stringmap.ObjectTypeCode equals entity.ObjectTypeCode
        where entity.Name == "New_Connection"

また、Cap / Dir/EPがnull許容かどうかを確認してください

于 2012-06-06T05:30:06.493 に答える