Entity Framework, EF, Extra call to DataBase on Parent Table

Vote count:

0

My model is simple

    public partial class Customer
{
    public Customer()
    {
        this.Orders = new HashSet<Order>();
    }
    public int Id { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Order> Orders { get; set; }
}

public partial class Order
{
    public Order()
    {
        this.OrderDetails = new HashSet<OrderDetail>();
    }
    public int Id { get; set; }
    public string OrderDescription { get; set; }
    public int CustomerId { get; set; }
    public virtual Customer Customer { get; set; }
    public virtual ICollection<OrderDetail> OrderDetails { get; set; }
}
public partial class OrderDetail
{
    public int Id { get; set; }
    public int OrderId { get; set; }
    public string ProductName { get; set; }
}

This code was generated using EF's edmx file. Then i generated database form this model. I am doing EagerLoad to fetch Data.

    public virtual IQueryable<T> GetAllEagerLoadSelective(string[] children)
    {
        foreach (var item in children)
        {
            DbSet.Include(item).Load();
        }
        return DbSet;
    } 

and my call looks like

        string[] Navs = { "OrderDetails" };
        var orders = VNUow.Order.GetAllEagerLoadSelective(Navs);
        var temp = orders.ToList();
        return temp;

LazyLoading = false There are two queries being run, The first one makes sense

SELECT 
[Project1].[Id] AS [Id], 
[Project1].[OrderDescription] AS [OrderDescription], 
[Project1].[CustomerId] AS [CustomerId], 
[Project1].[C1] AS [C1], 
[Project1].[Id1] AS [Id1], 
[Project1].[OrderId] AS [OrderId], 
[Project1].[ProductName] AS [ProductName]
FROM ( SELECT 
    [Extent1].[Id] AS [Id], 
    [Extent1].[OrderDescription] AS [OrderDescription], 
    [Extent1].[CustomerId] AS [CustomerId], 
    [Extent2].[Id] AS [Id1], 
    [Extent2].[OrderId] AS [OrderId], 
    [Extent2].[ProductName] AS [ProductName], 
    CASE WHEN ([Extent2].[Id] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1]
    FROM  [dbo].[Orders] AS [Extent1]
    LEFT OUTER JOIN [dbo].[OrderDetails] AS [Extent2] ON [Extent1].[Id] = [Extent2].[OrderId]
)  AS [Project1]
ORDER BY [Project1].[Id] ASC, [Project1].[C1] ASC

go

but Why there is this second query ? A select on the parent table

SELECT 
[Extent1].[Id] AS [Id], 
[Extent1].[OrderDescription] AS [OrderDescription], 
[Extent1].[CustomerId] AS [CustomerId]
FROM [dbo].[Orders] AS [Extent1]

go

asked 3 mins ago

user2624698

1