このクロス集計型の問合せをLinq（表とデータの提供）に書く方法

Question

これは単純なクロス集計問合せです。私はSQL知識をLinqに転送するのが難しいです。テストするのが難しいため（私はWP7開発のためにlinqpadを正しく実行できませんでした）、私は本当に簡単にプレイできません。 LINQでのSQLクエリ文の1翻訳：以下

は

CREATE TABLE Store 
(
    StoreID INT NOT NULL, 
    StoreName VARCHAR(10) NOT NULL 
) 

INSERT INTO Store (StoreID,StoreName) VALUES (1,'Store A') 
INSERT INTO Store (StoreID,StoreName) VALUES (2,'Store B') 

CREATE TABLE ProductType 
(
    ProductTypeID INT NOT NULL, 
    ProductTypeName VARCHAR(20) NOT NULL 
) 

INSERT INTO ProductType (ProductTypeID,ProductTypeName) VALUES (1,'Clothing') 
INSERT INTO ProductType (ProductTypeID,ProductTypeName) VALUES (2,'Food') 

CREATE TABLE Product 
(
    ProductID INT NOT NULL, 
    ProductTypeID INT NOT NULL, 
    ProductName VARCHAR(20) NOT NULL 
) 

INSERT INTO Product (ProductID,ProductTypeID,ProductName) VALUES (1,1,'Hat') 
INSERT INTO Product (ProductID,ProductTypeID,ProductName) VALUES (2,1,'Shirt') 
INSERT INTO Product (ProductID,ProductTypeID,ProductName) VALUES (3,1,'Pant') 
INSERT INTO Product (ProductID,ProductTypeID,ProductName) VALUES (4,2,'Orange') 
INSERT INTO Product (ProductID,ProductTypeID,ProductName) VALUES (5,2,'Apple') 


CREATE TABLE Purchase 
(
    PurchaseID INT NOT NULL, 
    ProductID INT NOT NULL, 
    StoreID INT NOT NULL, 
    Quantity INT NULL, 
    Amount INT NULL 
) 

INSERT INTO Purchase (PurchaseID,ProductID,StoreID,Quantity,Amount) VALUES (1,1,1,5,10) 
INSERT INTO Purchase (PurchaseID,ProductID,StoreID,Quantity,Amount) VALUES (2,2,1,4,12) 
INSERT INTO Purchase (PurchaseID,ProductID,StoreID,Quantity,Amount) VALUES (3,3,1,1,10) 
INSERT INTO Purchase (PurchaseID,ProductID,StoreID,Quantity,Amount) VALUES (4,4,1,3,16) 
INSERT INTO Purchase (PurchaseID,ProductID,StoreID,Quantity,Amount) VALUES (5,5,1,7,12) 
INSERT INTO Purchase (PurchaseID,ProductID,StoreID,Quantity,Amount) VALUES (6,1,2,10,22) 
INSERT INTO Purchase (PurchaseID,ProductID,StoreID,Quantity,Amount) VALUES (7,2,2,8,26) 


SELECT s.StoreName 
    ,SUM(CASE 
     WHEN t.ProductTypeID=1 THEN Amount 
     ELSE 0 
    END) as ClothingAmount 
    ,SUM(CASE 
     WHEN t.ProductTypeID=2 THEN Amount 
     ELSE 0 
    END)AS FoodQuantity 
    ,SUM(CASE 
     WHEN t.ProductTypeID=1 THEN Quantity 
     ELSE 0 
    END) as ClothingAmount 
    ,SUM(CASE 
     WHEN t.ProductTypeID=2 THEN Quantity 
     ELSE 0 
    END)AS FoodQuantity 
FROM Purchase u 
INNER JOIN Product r 
ON u.ProductID=r.ProductID 
INNER JOIN ProductType t 
ON r.ProductTypeID=t.ProductTypeID 
INNER JOIN Store s 
ON s.StoreID=u.StoreID 
GROUP BY s.StoreName 

Answer 1

1であるが、それがあることを

SELECT SUM(
    (CASE 
     WHEN [t2].[ProductTypeID] = @p0 THEN [t0].[Amount] 
     ELSE @p1 
    END)) AS [ClothingAmount], SUM(
    (CASE 
     WHEN [t2].[ProductTypeID] = @p2 THEN [t0].[Amount] 
     ELSE @p3 
    END)) AS [FoodAmount], SUM(
    (CASE 
     WHEN [t2].[ProductTypeID] = @p4 THEN [t0].[Quantity] 
     ELSE @p5 
    END)) AS [ClothingQuantity], SUM(
    (CASE 
     WHEN [t2].[ProductTypeID] = @p6 THEN [t0].[Quantity] 
     ELSE @p7 
    END)) AS [FoodQuantity], [t3].[StoreName] 
FROM [Purchase] AS [t0] 
INNER JOIN [Product] AS [t1] ON [t0].[ProductID] = [t1].[ProductID] 
INNER JOIN [ProductType] AS [t2] ON [t1].[ProductTypeID] = [t2].[ProductTypeID] 
INNER JOIN [Store] AS [t3] ON [t0].[StoreID] = [t3].[StoreID] 
GROUP BY [t3].[StoreName] 

注：以下のSQLに翻訳さ

from u in Purchases 
join r in Products on u.ProductID equals r.ProductID 
join t in ProductTypes on r.ProductTypeID equals t.ProductTypeID 
join s in Stores on u.StoreID equals s.StoreID 
group new {Purchase = u, Product = r, ProductType = t, Store = s} by s.StoreName into grouped 
select new { 
    StoreName = grouped.Key, 
    ClothingAmount = grouped.Sum(entry => entry.ProductType.ProductTypeID == 1 ? entry.Purchase.Amount : 0), 
    FoodAmount = grouped.Sum(entry => entry.ProductType.ProductTypeID == 2 ? entry.Purchase.Amount : 0), 
    ClothingQuantity = grouped.Sum(entry => entry.ProductType.ProductTypeID == 1 ? entry.Purchase.Quantity : 0), 
    FoodQuantity = grouped.Sum(entry => entry.ProductType.ProductTypeID == 2 ? entry.Purchase.Quantity : 0) 
} 

適切なプライマリキーと外部キーをテーブルに設定することを強くお勧めします。これが完了すると（それに応じてモデルも更新されます）、同じクエリを次のように減らすことができます：

from purchase in Purchases 
group purchase by purchase.Store.StoreName into grouped 
select new { 
    StoreName = grouped.Key, 
    ClothingAmount = grouped.Sum(purchase => purchase.Product.ProductTypeID == 1 ? purchase.Amount : 0), 
    FoodAmount = grouped.Sum(purchase => purchase.Product.ProductTypeID == 2 ? purchase.Amount : 0), 
    ClothingQuantity = grouped.Sum(purchase => purchase.Product.ProductTypeID == 1 ? purchase.Quantity : 0), 
    FoodQuantity = grouped.Sum(purchase => purchase.Product.ProductTypeID == 2 ? purchase.Quantity : 0) 
}