我有一个简单的联接查询，连接两个表（一个类别有很多产品）：

using (ProdContext db = new ProdContext())
{
    var query = from category in db.Categories
                join product in db.Products
                     on category.CategoryID equals product.CategoryID into productList
                select new
                       {
                           categoryName = category.Name,products = productList
                       };

    foreach (var c in query)
    {
        Console.WriteLine("* {0}",c.categoryName);

        foreach (var p in c.products)
        {
             Console.WriteLine("   - {0}",p.Name);
        }
    };
}

对于课程：

class Category
{
    public int CategoryID { get; set; }
    public String Name { get; set; }
    public List<Product> Products { get; set; }
}

class Product
{
    public int ProductID { get; set; }
    public String Name { get; set; }
    public int UnitsInStock { get; set; }
    public int CategoryID { get; set; }
}

class ProdContext : DbContext
{
    public DbSet<Category> Categories { get; set; }
    public DbSet<Product> Products { get; set; }
}

，通常一切正常，但是当我开始尝试快速加载和延迟加载时，我感到困惑，因为无论我在查询的末尾添加.ToList()还是我的SQL请求总是这样：

SELECT 
    [Project1].[CategoryID] AS [CategoryID],[Project1].[Name] AS [Name],[Project1].[C1] AS [C1],[Project1].[ProductID] AS [ProductID],[Project1].[Name1] AS [Name1],[Project1].[UnitsInStock] AS [UnitsInStock],[Project1].[CategoryID1] AS [CategoryID1],FROM 
    (SELECT 
         [Extent1].[CategoryID] AS [CategoryID],[Extent1].[Name] AS [Name],[Extent2].[ProductID] AS [ProductID],[Extent2].[Name] AS [Name1],[Extent2].[UnitsInStock] AS [UnitsInStock],[Extent2].[CategoryID] AS [CategoryID1],CASE WHEN ([Extent2].[ProductID] IS NULL) 
            THEN CAST(NULL AS int) ELSE 1 END AS [C1]
     FROM  
         [dbo].[Categories] AS [Extent1]
     LEFT OUTER JOIN  
         [dbo].[Products] AS [Extent2] ON [Extent1].[CategoryID] = [Extent2].[CategoryID])  AS [Project1]
ORDER BY 
    [Project1].[CategoryID] ASC,[Project1].[C1] ASC

据我了解，当我使用.ToList()（急切加载）时，它应该看起来像这样，但是当我使用（默认）延迟加载时，它应该发送许多sql请求，询问关于foreach循环的所有元素分别。我的问题是-为什么没有区别，总是只发送一个SQL？