編集
以下のテストは、SQLServerとSqlClientを使用して行われました。 プロバイダーとして。問題がSQLServerで再現できないという事実は、MySqlの場合に疑問を投げかけます。 使用しているプロバイダーには、LINQクエリに対して誤ったSQLを作成するというバグがあります。 この質問
と同じ問題のようです MySqlで問題が発生した場所 プロバイダーも同様であり、SqlClientでは再現できませんでした /SQLServer。
太字の例（EF 4.3.1を使用）をテストしましたが、問題を再現できません：
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
namespace EFInclude
{
public class Harbor
{
public int HarborId { get; set; }
public virtual ICollection<Ship> Ships { get; set; }
public string Description { get; set; }
}
public class Ship
{
public int ShipId { get; set; }
public int HarborId { get; set; }
public virtual Harbor Harbor { get; set; }
public virtual ICollection<CrewMember> CrewMembers { get; set; }
public string Description { get; set; }
}
public class CrewMember
{
public int CrewMemberId { get; set; }
public int ShipId { get; set; }
public virtual Ship Ship { get; set; }
public int RankId { get; set; }
public virtual Rank Rank { get; set; }
public int ClearanceId { get; set; }
public virtual Clearance Clearance { get; set; }
public string Description { get; set; }
}
public class Rank
{
public int RankId { get; set; }
public virtual ICollection<CrewMember> CrewMembers { get; set; }
public string Description { get; set; }
}
public class Clearance
{
public int ClearanceId { get; set; }
public virtual ICollection<CrewMember> CrewMembers { get; set; }
public string Description { get; set; }
}
public class MyContext : DbContext
{
public DbSet<Harbor> Harbors { get; set; }
public DbSet<Ship> Ships { get; set; }
public DbSet<CrewMember> CrewMembers { get; set; }
public DbSet<Rank> Ranks { get; set; }
public DbSet<Clearance> Clearances { get; set; }
}
class Program
{
static void Main(string[] args)
{
Database.SetInitializer(new DropCreateDatabaseAlways<MyContext>());
using (var context = new MyContext())
{
context.Database.Initialize(true);
var harbor = new Harbor
{
Ships = new HashSet<Ship>
{
new Ship
{
CrewMembers = new HashSet<CrewMember>
{
new CrewMember
{
Rank = new Rank { Description = "Rank A" },
Clearance = new Clearance { Description = "Clearance A" },
Description = "CrewMember A"
},
new CrewMember
{
Rank = new Rank { Description = "Rank B" },
Clearance = new Clearance { Description = "Clearance B" },
Description = "CrewMember B"
}
},
Description = "Ship AB"
},
new Ship
{
CrewMembers = new HashSet<CrewMember>
{
new CrewMember
{
Rank = new Rank { Description = "Rank C" },
Clearance = new Clearance { Description = "Clearance C" },
Description = "CrewMember C"
},
new CrewMember
{
Rank = new Rank { Description = "Rank D" },
Clearance = new Clearance { Description = "Clearance D" },
Description = "CrewMember D"
}
},
Description = "Ship CD"
}
},
Description = "Harbor ABCD"
};
context.Harbors.Add(harbor);
context.SaveChanges();
}
using (var context = new MyContext())
{
DbSet<Harbor> dbSet = context.Set<Harbor>();
IQueryable<Harbor> query = dbSet;
query = query.Include(entity => entity.Ships);
query = query.Include(entity => entity.Ships.Select(s => s.CrewMembers));
query = query.Include(entity => entity.Ships.Select(s => s.CrewMembers.Select(cm => cm.Rank)));
query = query.Include(entity => entity.Ships.Select(s => s.CrewMembers.Select(cm => cm.Clearance)));
var sqlString = query.ToString();
// see below for the generated SQL query
var harbor = query.Single();
Console.WriteLine("Harbor {0} Description = \"{1}\"",
harbor.HarborId, harbor.Description);
foreach (var ship in harbor.Ships)
{
Console.WriteLine("- Ship {0} Description = \"{1}\"",
ship.ShipId, ship.Description);
foreach (var crewMember in ship.CrewMembers)
{
Console.WriteLine("-- CrewMember {0} Description = \"{1}\"",
crewMember.CrewMemberId, crewMember.Description);
Console.WriteLine("-- CrewMember {0} Rank Description = \"{1}\"",
crewMember.CrewMemberId, crewMember.Rank.Description);
Console.WriteLine("-- CrewMember {0} Clearance Description = \"{1}\"",
crewMember.CrewMemberId, crewMember.Clearance.Description);
}
}
Console.ReadLine();
}
}
}
}
出力は次のとおりです。
太字の説明によると、次のようになります。 CrewMember 1 Description ="Rank A" 他の3人の乗組員も同じように混乱しました。しかし、私はこれをしていません。
エラーが発生したコードと比較して、私のテストプログラムには何か違いがありますか？
編集
クエリ用に生成されたSQL（var sqlString = query.ToString();の行を参照してください。 上記のソースコードで、以下はsqlStringの内容です。 ）は：
SELECT
[Project1].[HarborId] AS [HarborId],
[Project1].[Description] AS [Description],
[Project1].[C2] AS [C1],
[Project1].[ShipId] AS [ShipId],
[Project1].[HarborId1] AS [HarborId1],
[Project1].[Description1] AS [Description1],
[Project1].[C1] AS [C2],
[Project1].[CrewMemberId] AS [CrewMemberId],
[Project1].[ShipId1] AS [ShipId1],
[Project1].[RankId] AS [RankId],
[Project1].[ClearanceId] AS [ClearanceId],
[Project1].[Description2] AS [Description2],
[Project1].[RankId1] AS [RankId1],
[Project1].[Description3] AS [Description3],
[Project1].[ClearanceId1] AS [ClearanceId1],
[Project1].[Description4] AS [Description4]
FROM ( SELECT
[Extent1].[HarborId] AS [HarborId],
[Extent1].[Description] AS [Description],
[Join3].[ShipId1] AS [ShipId],
[Join3].[HarborId] AS [HarborId1],
[Join3].[Description1] AS [Description1],
[Join3].[CrewMemberId] AS [CrewMemberId],
[Join3].[ShipId2] AS [ShipId1],
[Join3].[RankId1] AS [RankId],
[Join3].[ClearanceId1] AS [ClearanceId],
[Join3].[Description2] AS [Description2],
[Join3].[RankId2] AS [RankId1],
[Join3].[Description3] AS [Description3],
[Join3].[ClearanceId2] AS [ClearanceId1],
[Join3].[Description4] AS [Description4],
CASE WHEN ([Join3].[ShipId1] IS NULL) THEN CAST(NULL AS int) WHEN ([Join3].[CrewMemberId] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1],
CASE WHEN ([Join3].[ShipId1] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C2]
FROM [dbo].[Harbors] AS [Extent1]
LEFT OUTER JOIN (SELECT [Extent2].[ShipId] AS [ShipId1], [Extent2].[HarborId] AS [HarborId], [Extent2].[Description] AS [Description1], [Join2].[CrewMemberId], [Join2].[ShipId2], [Join2].[RankId1], [Join2].[ClearanceId1], [Join2].[Description2], [Join2].[RankId2], [Join2].[Description3], [Join2].[ClearanceId2], [Join2].[Description4]
FROM [dbo].[Ships] AS [Extent2]
LEFT OUTER JOIN (SELECT [Extent3].[CrewMemberId] AS [CrewMemberId], [Extent3].[ShipId] AS [ShipId2], [Extent3].[RankId] AS [RankId1], [Extent3].[ClearanceId] AS [ClearanceId1], [Extent3].[Description] AS [Description2], [Extent4].[RankId] AS [RankId2], [Extent4].[Description] AS [Description3], [Extent5].[ClearanceId] AS [ClearanceId2], [Extent5].[Description] AS [Description4]
FROM [dbo].[CrewMembers] AS [Extent3]
INNER JOIN [dbo].[Ranks] AS [Extent4] ON [Extent3].[RankId] = [Extent4].[RankId]
LEFT OUTER JOIN [dbo].[Clearances] AS [Extent5] ON [Extent3].[ClearanceId] = [Extent5].[ClearanceId] ) AS [Join2] ON [Extent2].[ShipId] = [Join2].[ShipId2] ) AS [Join3] ON [Extent1].[HarborId] = [Join3].[HarborId]
) AS [Project1]
ORDER BY [Project1].[HarborId] ASC, [Project1].[C2] ASC, [Project1].[ShipId] ASC, [Project1].[C1] ASC