整合多个查询到一个与EF这样吗？(Aggregating multiple queries into

我在我的应用程序中使用EF 4.0 POCO。 有什么缺点来获取这样的信息？

给定一个customerId和productId ，我想申请，要求我从需要多个查询数据库获取大量的信息蝇头件的一些业务规则。相反，我可以写一个查询，如下所示：

var customerId = 1;
var productId = 1;

var aggregateQuery = 
    from entry in Customers.Take(0).DefaultIfEmpty()
    select new
    {
        numberOfOrders = SalesOrderHeaders.Where (header => header.CustomerID == customerId).Count(),
        canSellProduct = Products.Where(product => product.ProductID == productId && product.SellEndDate > DateTime.Now).Count () > 0

        //more infromation of this sort, required to enforce business rules
    };

var informationPacket = aggregateQuery.First();

该Customers.Take(0).DefaultIfEmpty()只是提供了一种方式来启动查询和Customers ， SalesOrderHeaders和Products都是从上下文EF的ObjectQuery实例（这个例子如果从LinqPad）。这将导致以下SQL：

-- Region Parameters
DECLARE @p0 Int = 1
DECLARE @p1 Int = 1
DECLARE @p2 DateTime = '2012-04-04 21:02:20.798'
DECLARE @p3 Int = 0
-- EndRegion
SELECT TOP (1) [t6].[value] AS [numberOfOrders], [t6].[value2] AS [canSellProduct]
FROM (
    SELECT (
        SELECT COUNT(*)
        FROM [Sales].[SalesOrderHeader] AS [t3]
        WHERE [t3].[CustomerID] = @p0
        ) AS [value], 
        (CASE 
            WHEN ((
                SELECT COUNT(*)
                FROM [Production].[Product] AS [t5]
                WHERE ([t5].[ProductID] = @p1) AND ([t5].[SellEndDate] > @p2)
                )) > @p3 THEN 1
            WHEN NOT (((
                SELECT COUNT(*)
                FROM [Production].[Product] AS [t5]
                WHERE ([t5].[ProductID] = @p1) AND ([t5].[SellEndDate] > @p2)
                )) > @p3) THEN 0
            ELSE NULL
         END) AS [value2]
    FROM (
        SELECT NULL AS [EMPTY]
        ) AS [t0]
    OUTER APPLY (
        SELECT TOP (0) NULL AS [EMPTY]
        FROM [Sales].[Customer] AS [t1]
        ) AS [t2]
    ) AS [t6]

我瘦到使用单独的查询，原因有三：