CodeGo.net> .include方法是否在LINQ中命中数据库？

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我正在测试下面的Linq查询.我正在检查日志以查看是否有数据库命中：

var productEntities = _context.Set<Product>()
                .Include(p => p.OrderItems)
                .Include(p => p.OrderItems.Select(oi => oi.Order))
                .Include(p => p.OrderItems.Select(oi => oi.Order.Client));

            Console.WriteLine(productEntities.Count());

无论我是否注释掉对Count()的调用,日志都会显示以下相同输出：

06001

SELECT Count(*) FROM INFORMATION_SCHEMA.TABLES AS t WHERE
t.TABLE_SCHEMA + ‘.’ + t.TABLE_NAME IN
(‘dbo.AccountRecords’,’dbo.Products’,’dbo.Doughs’,’dbo.OrderItems’,’dbo.Orders’,’dbo.Clients’,’dbo.ShippingInformations’,’dbo.OrderSpecialClients’,’dbo.OrderSpecialProducts’,’dbo.Taxes’,’dbo.FixedOrders’,’dbo.FixedOrderItems’,’dbo.OrderSubstitutions’,’dbo.OrderPerformanceLog’)
OR t.TABLE_NAME = ‘EdmMetadata’
— Executing at 8/20/2016 3:32:53 PM -04:00
— Completed in 2 ms with result: 14

Closed connection at 8/20/2016 3:32:53 PM -04:00 Opened connection at
8/20/2016 3:32:53 PM -04:00 SELECT
[GroupBy1].[A1] AS [C1]
FROM ( SELECT
COUNT(1) AS [A1]
FROM [dbo].[__MigrationHistory] AS [Extent1]
WHERE [Extent1].[ContextKey] = @p__linq__0
) AS [GroupBy1]
— p__linq__0: ‘Arhoma.Core.Data.ArhomaContext’ (Type = String, Size = 4000)
— Executing at 8/20/2016 3:32:53 PM -04:00
— Failed in 51 ms with error: Invalid object name ‘dbo.__MigrationHistory’.

Closed connection at 8/20/2016 3:32:53 PM -04:00 Opened connection at
8/20/2016 3:32:53 PM -04:00 SELECT
[GroupBy1].[A1] AS [C1]
FROM ( SELECT
COUNT(1) AS [A1]
FROM [dbo].[__MigrationHistory] AS [Extent1]
) AS [GroupBy1]
— Executing at 8/20/2016 3:32:53 PM -04:00
— Failed in 36 ms with error: Invalid object name ‘dbo.__MigrationHistory’.

Closed connection at 8/20/2016 3:32:53 PM -04:00 Opened connection at
8/20/2016 3:32:53 PM -04:00 SELECT
[GroupBy1].[A1] AS [C1]
FROM ( SELECT
COUNT(1) AS [A1]
FROM [dbo].[Products] AS [Extent1]
) AS [GroupBy1]
— Executing at 8/20/2016 3:32:53 PM -04:00
— Completed in 0 ms with result: SqlDataReader

Closed connection at 8/20/2016 3:32:53 PM -04:00 299

我的问题：为什么它会打入数据库？我以为是在添加.ToList()之类的东西或调用.Count()时做出的？但是,即使我删除了对Count()的调用,它仍然会命中数据库.所以现在我在想,是否是.include迫使数据库命中？

解决方法:

所有这些与MigrationHistory相关的查询仅在代码首次连接到数据库时运行一次. EF仅尝试验证是否需要将数据库升级到较新版本.

要确认这一点,请在您提出的查询之前尝试任何有意义的查询,以使带有Includes的查询成为第二个查询.您将看到所有这些版本控制噪音,然后是您的第一个查询,然后没有任何内容,因为Include本身未检索任何内容.

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