Vb.net 如何使用Linq查询具有group by和两个计数的实体

我需要一个问题的帮助。我想返回一个实体列表，对于每个实体，我需要两个计数

使用从Those表生成的实体：

    /****** Objet :  Table [dbo].[Messages]    Date de génération du script : 03/12/2013 15:31:06 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
DROP TABLE [dbo].[Messages]
Go
CREATE TABLE [dbo].[Messages](
    [MessageID] [int] IDENTITY(1,1) NOT NULL,
    [UserCreation] [nvarchar](20) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [DateCreation] [datetime] NOT NULL  DEFAULT (getdate()),
    [UserModif] [nvarchar](20) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [DateModif] [datetime] NOT NULL  DEFAULT (getdate()),
    [Timestamp] [timestamp] NOT NULL,
    [Notification] [bit] NOT NULL  DEFAULT ((0)),
    [BounceTraite] [bit] NOT NULL  DEFAULT ((0)),
 CONSTRAINT [PK_Messages] PRIMARY KEY CLUSTERED 
(
    [MessageID] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

GO
/****** Objet :  Table [dbo].[MessageLocalisations]    Date de génération du script : 03/12/2013 15:31:06 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
DROP TABLE [dbo].[MessageLocalisations]
Go
CREATE TABLE [dbo].[MessageLocalisations](
    [MessageID] [int] NOT NULL,
    [CodeLocalisation] [char](5) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [From] [nvarchar](100) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [Subject] [nvarchar](255) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [Message] [nvarchar](max) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [TargetedAudience] [nvarchar](255) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
 CONSTRAINT [PK_MessageLocalisations] PRIMARY KEY CLUSTERED 
(
    [MessageID] ASC,
    [CodeLocalisation] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF
GO
/****** Objet :  Table [dbo].[MessageRecipients]    Date de génération du script : 03/12/2013 15:31:06 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
DROP TABLE [dbo].[MessageRecipients]
Go
CREATE TABLE [dbo].[MessageRecipients](
    [MessageID] [int] NOT NULL,
    [Recipient] [nvarchar](20) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [DateRead] [datetime] NULL,
    [Email] [nvarchar](60) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [Bounce] [bit] NOT NULL,
    [DateCreation] [datetime] NOT NULL,
    [DateModif] [datetime] NOT NULL ,
 CONSTRAINT [PK_MessageRecipients] PRIMARY KEY CLUSTERED 
(
    [MessageID] ASC,
    [Recipient] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF
GO

在我的示例中，我的实体是消息。我需要一个收件人计数和一个已阅读邮件的收件人计数：

    (From msg In context.Messages.Include("MessageLocalisations")
                         Let countRecipients = msg.MessageRecipients.Count
                         Let countRecipientsRead = msg.MessageRecipients.Where(Function(x) x.DateRead.HasValue).Count
                         Where (msg.UserCreation.Equals(user, StringComparison.OrdinalIgnoreCase))
                         Group By msg.MessageID Into Group
                         Select msg, Group).ToList()

我的例子不起作用。我的select语句出错，他无法识别msg。在LINQ中，当我使用GROUPBY时，我不确定Group是如何工作的以及select是如何工作的

我想要的结果是一个消息列表，其中包括MessageLocalizations、每条消息的收件人数、阅读每条消息的收件人数

---

谢谢你的帮助！在SQL中，这非常简单…：（

以下是最终解决我问题的查询：

context.MessageSecuriseJeu.Include("MessageSecuriseLocalisations").
                            Where(Function(w) w.UtilisateurCreation.Equals(codeUtilisateurExpediteur, StringComparison.CurrentCultureIgnoreCase)).
                            Select(Function(msg) New With {.msg = msg, .nbrDest = msg.MessageSecuriseDestinataires.Count, .nbrLu = msg.MessageSecuriseDestinataires.Where(Function(w) w.DateLecture.HasValue).Count}).tolist()

---

可以发布表定义（创建表语句）吗？你在哪里使用这些

let

语句？我想在结果中使用它们，这样我可以在UI中显示计数。我可能不需要它们。我完全是n00b，带有Linq to实体。添加了Create tables语句。我必须在发布之前对它们进行一些修改，但我认为它们可以正常工作。T他的链接帮助了我。也许我的问题是重复的：[[1]：