Язык программирования C#9 и платформа .NET5

[Fact]
public void ShouldGetCarsOnOrderWithRelatedPropertiesAsSplitQuery()
{
  IQueryable<Car> query = Context.Cars.Where(c => c.Orders.Any())
    .Include(c => c.MakeNavigation)
    .Include(c => c.Orders).ThenInclude(o => o.CustomerNavigation)
    <b>.AsSplitQuery()</b>;
  var cars = query.ToList();
  Assert.Equal(4, cars.Count);
  cars.ForEach(c =&gt;
  {
    Assert.NotNull(c.MakeNavigation);
    Assert.NotNull(c.Orders.ToList()[0].CustomerNavigation);
  });
}
Метод 
ToQueryString()
 возвращает только первый запрос, поэтому последующие запросы были получены с применением профилировщика SQL Server:
SELECT [i].[Id], [i].[Color], [i].[IsDrivable], [i].[MakeId],
       [i].[PetName], [i].
[TimeStamp], [m].[Id], [m].[Name], [m].[TimeStamp]
FROM [dbo].[Inventory] AS [i]
INNER JOIN [dbo].[Makes] AS [m] ON [i].[MakeId] = [m].[Id]
WHERE ([i].[IsDrivable] = CAST(1 AS bit)) AND EXISTS (
SELECT 1
    FROM [Dbo].[Orders] AS [o]
    INNER JOIN (
      SELECT [i0].[Id], [i0].[Color], [i0].[IsDrivable], [i0].[MakeId],
             [i0].[PetName], 
[i0].[TimeStamp]
      FROM [dbo].[Inventory] AS [i0]
      WHERE [i0].[IsDrivable] = CAST(1 AS bit)
    ) AS [t] ON [o].[CarId] = [t].[Id]
    WHERE ([t].[IsDrivable] = CAST(1 AS bit)) AND ([i].[Id] = [o].[CarId]))
ORDER BY [i].[Id], [m].[Id]
SELECT [t0].[Id], [t0].[CarId], [t0].[CustomerId], [t0].[TimeStamp],
       [t0].[Id1], [t0].
[TimeStamp1], [t0].[FirstName], [t0].[FullName],
       [t0].[LastName], [i].[Id], [m].[Id]
FROM [dbo].[Inventory] AS [i]
INNER JOIN [dbo].[Makes] AS [m] ON [i].[MakeId] = [m].[Id]
INNER JOIN (
  SELECT [o].[Id], [o].[CarId], [o].[CustomerId], [o].[TimeStamp],
         [c].[Id] AS [Id1], [c].
[TimeStamp] AS [TimeStamp1], [c].[FirstName],
         [c].[FullName], [c].[LastName]
  FROM [Dbo].[Orders] AS [o]
  INNER JOIN (
    SELECT [i0].[Id], [i0].[IsDrivable]
 
    FROM [dbo].[Inventory] AS [i0]
    WHERE [i0].[IsDrivable] = CAST(1 AS bit)
  ) AS [t] ON [o].[CarId] = [t].[Id]
    INNER JOIN [Dbo].[Customers] AS [c] ON [o].[CustomerId] = [c].[Id]
    WHERE [t].[IsDrivable] = CAST(1 AS bit)
) AS [t0] ON [i].[Id] = [t0].[CarId]
WHERE ([i].[IsDrivable] = CAST(1 AS bit)) AND EXISTS (
    SELECT 1
    FROM [Dbo].[Orders] AS [o0]
    INNER JOIN (
      SELECT [i1].[Id], [i1].[Color], [i1].[IsDrivable], [i1].[MakeId],
             [i1].[PetName], 
[i1].[TimeStamp]
      FROM [dbo].[Inventory] AS [i1]
      WHERE [i1].[IsDrivable] = CAST(1 AS bit)
    ) AS [t1] ON [o0].[CarId] = [t1].[Id]
    WHERE ([t1].[IsDrivable] = CAST(1 AS bit)) AND ([i].[Id] = [o0].[CarId]))
ORDER BY [i].[Id], [m].[Id]
Будете вы разделять свои запросы или нет, зависит от существующих бизнес-требований.
  
Фильтрация связанных данных
 
В версии EF Core 5 появилась возможность фильтрации при включении навигационных свойств типа коллекций. До выхода EF Core 5 единственным способом получения отфильтрованного списка для навигационного свойства типа коллекций было использование явной загрузки. Добавьте в 
MakeTests.cs
 следующий тест, который демонстрирует получение записей производителей, выпускающих автомобили желтого цвета:
[Fact]
public void ShouldGetAllMakesAndCarsThatAreYellow()
{
  var query = Context.Makes.IgnoreQueryFilters()
<b>      .Include(x =&gt; x.Cars.Where(x =&gt; x.Color == &quot;Yellow&quot;));</b>
     var qs = query.ToQueryString();
  var makes = query.ToList();
  Assert.NotNull(makes);
  Assert.NotEmpty(makes);
  Assert.NotEmpty(makes.Where(x =&gt; x.Cars.Any()));
  Assert.Empty(makes.First(m =&gt; m.Id == 1).Cars);
  Assert.Empty(makes.First(m =&gt; m.Id == 2).Cars);
  Assert.Empty(makes.First(m =&gt; m.Id == 3).Cars);
  Assert.Single(makes.First(m =&gt; m.Id == 4).Cars);
  Assert.Empty(makes.First(m =&gt; m.Id == 5).Cars);
}
Ниже показан сгенерированный код SQL: