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ここにコードを入力してください 'let'キーワードを使用するいくつかのLinqクエリがあります。彼らは3.5でうまく動作しますが、私は4.0で非常に奇妙な動作を見ています。3.5と比較して4.0で異なる動作をするLinqクエリ
例：
var query1 =
(from xVehicleOption in this.entities.VehicleOptionSet
let regionPriceAdjustment = (from xOptionRegionPriceAdjustmentLeftOuter in this.entities.OptionRegionPriceAdjustmentSet
where xOptionRegionPriceAdjustmentLeftOuter.VehicleTypeRegionId == this.vehicleTypeRegionId
&& xOptionRegionPriceAdjustmentLeftOuter.VehicleId == this.vehicleId
&& xOptionRegionPriceAdjustmentLeftOuter.VehicleOptionId == xVehicleOption.VehicleOptionId
select new
{
xOptionRegionPriceAdjustmentLeftOuter,
xOptionRegionPriceAdjustmentLeftOuter.xPriceType
})
where xVehicleOption.VehicleId == this.vehicleId
&& (xVehicleOption.OptionTypeId == 5 || xVehicleOption.OptionTypeId == 7)
select new
{
Name = xVehicleOption.DisplayName,
VehicleOptionId = xVehicleOption.VehicleOptionId,
SortOrder = xVehicleOption.SortOrder,
OptionAvailability = xVehicleOption.OptionAvailabilityDisplayName,
IsDefaultConfiguration = xVehicleOption.IsDefaultConfiguration,
OptionType = xVehicleOption.OptionTypeDisplayName,
RegionPriceAdjustment = regionPriceAdjustment
}).OrderBy(o => o.SortOrder);
これは2つのネストされたループを列挙することを可能にします。オプション内に1つ、オプション内で各地域調整用に1つ。
foreach (var bookOption in query)
{
.......
foreach (var regionAdjustment in bookOption.RegionPriceAdjustment)
{
.......
}
}
4.0の問題は、生成されたSQLは、（プロファイラでトレース）は、任意のWHERE句なしRegionPriceAdjustmentテーブルからの選択であることです。これは、コマンドがタイムアウトすることを意味します（問合せの他の部分の兆候がないため、とにかく間違っています）。
"let"を.Includeに置き換えようとしましたが、これは遅延読み込みを有効にしても動作しますが、各PriceTypeの動的SQL文が生成されます（8個あります）。私は遅延読み込みを無効にしようとしましたが、これは間違いなくPriceTypeが読み込まれないためエラーです。私は2つのセレクトを区切りで使用しようとしましたが、同じ問題が発生します。
4.0では、POCOとEntityFramework DLLにDbContextオブジェクトを使用しています。私はObjectContextを試してみませんでしたが、DbContextはObjectContextをラップするので、違いはありません。
これはなぜですか？助言がありますか？
おかげで、イヴ・
編集：ここでは
は3.5とSQLです：ここでは
[Project2].[VehicleOptionId] AS [VehicleOptionId],
[Project2].[DisplayName] AS [DisplayName],
[Project2].[OptionAvailabilityDisplayName] AS [OptionAvailabilityDisplayName],
[Project2].[IsDefaultConfiguration] AS [IsDefaultConfiguration],
[Project2].[SortOrder] AS [SortOrder],
[Project2].[VehicleOptionId1] AS [VehicleOptionId1],
[Project2].[CategoryId] AS [CategoryId],
[Project2].[CategoryId1] AS [CategoryId1],
[Project2].[DisplayName1] AS [DisplayName1],
[Project2].[C1] AS [C1],
[Project2].[C2] AS [C2],
[Project2].[VehicleOptionId2] AS [VehicleOptionId2],
[Project2].[VehicleTypeRegionId] AS [VehicleTypeRegionId],
[Project2].[VehicleId] AS [VehicleId],
[Project2].[PriceTypeId] AS [PriceTypeId],
[Project2].[PriceAdjustment] AS [PriceAdjustment],
[Project2].[ValueTypeId] AS [ValueTypeId],
[Project2].[PriceTypeId1] AS [PriceTypeId1],
[Project2].[DisplayName2] AS [DisplayName2]
FROM (SELECT
[Extent1].[VehicleOptionId] AS [VehicleOptionId],
[Extent1].[DisplayName] AS [DisplayName],
[Extent1].[OptionAvailabilityDisplayName] AS [OptionAvailabilityDisplayName],
[Extent1].[IsDefaultConfiguration] AS [IsDefaultConfiguration],
[Extent1].[SortOrder] AS [SortOrder],
[Extent2].[VehicleOptionId] AS [VehicleOptionId1],
[Extent2].[CategoryId] AS [CategoryId],
[Extent3].[CategoryId] AS [CategoryId1],
[Extent3].[DisplayName] AS [DisplayName1],
1 AS [C1],
[Project1].[VehicleOptionId] AS [VehicleOptionId2],
[Project1].[VehicleTypeRegionId] AS [VehicleTypeRegionId],
[Project1].[VehicleId] AS [VehicleId],
[Project1].[PriceTypeId] AS [PriceTypeId],
[Project1].[PriceAdjustment] AS [PriceAdjustment],
[Project1].[ValueTypeId] AS [ValueTypeId],
[Project1].[PriceTypeId1] AS [PriceTypeId1],
[Project1].[DisplayName] AS [DisplayName2],
[Project1].[C1] AS [C2]
FROM [dbo].[KBB_V3_VehicleOption] AS [Extent1]
INNER JOIN [dbo].[KBB_V3_VehicleOptionCategory] AS [Extent2] ON ([Extent1].[VehicleOptionId] = [Extent2].[VehicleOptionId]) OR (([Extent1].[VehicleOptionId] IS NULL) AND ([Extent2].[VehicleOptionId] IS NULL))
INNER JOIN [dbo].[KBB_V3_Category] AS [Extent3] ON ([Extent2].[CategoryId] = [Extent3].[CategoryId]) OR (([Extent2].[CategoryId] IS NULL) AND ([Extent3].[CategoryId] IS NULL))
LEFT OUTER JOIN (SELECT
[Extent4].[VehicleOptionId] AS [VehicleOptionId],
[Extent4].[VehicleTypeRegionId] AS [VehicleTypeRegionId],
[Extent4].[VehicleId] AS [VehicleId],
[Extent4].[PriceTypeId] AS [PriceTypeId],
[Extent4].[PriceAdjustment] AS [PriceAdjustment],
[Extent4].[ValueTypeId] AS [ValueTypeId],
[Extent5].[PriceTypeId] AS [PriceTypeId1],
[Extent5].[DisplayName] AS [DisplayName],
1 AS [C1]
FROM [dbo].[KBB_V3_OptionRegionPriceAdjustment] AS [Extent4]
LEFT OUTER JOIN [dbo].[KBB_V3_PriceType] AS [Extent5] ON [Extent4].[PriceTypeId] = [Extent5].[PriceTypeId]) AS [Project1] ON ([Project1].[VehicleTypeRegionId] = @p__linq__6) AND ([Project1].[VehicleId] = @p__linq__7) AND ([Project1].[VehicleOptionId] = [Extent1].[VehicleOptionId])
WHERE (4 = [Extent1].[OptionTypeId]) AND ([Extent1].[VehicleId] = @p__linq__9) AND (22 = [Extent3].[CategoryTypeId])
) AS [Project2]
ORDER BY [Project2].[SortOrder] ASC, [Project2].[VehicleOptionId] ASC, [Project2].[VehicleOptionId1] ASC, [Project2].[CategoryId] ASC, [Project2].[CategoryId1] ASC, [Project2].[C2] ASC',N'@p__linq__6 int,@p__linq__7 int,@p__linq__9 int',@p__linq__6=0,@p__linq__7=261637,@p__linq__9=261637
は私だけ（POCOのを使用して）4.1で得るものです：
SELECT
[Extent1].[VehicleOptionId] AS [VehicleOptionId],
[Extent1].[VehicleTypeRegionId] AS [VehicleTypeRegionId],
[Extent1].[VehicleId] AS [VehicleId],
[Extent1].[PriceTypeId] AS [PriceTypeId],
[Extent1].[PriceAdjustment] AS [PriceAdjustment],
[Extent1].[ValueTypeId] AS [ValueTypeId]
FROM [dbo].[KBB_V3_OptionRegionPriceAdjustment] AS [Extent1]
ご覧のとおり、WHERE句はなく、残りのSQLのトレースもありません......