与 EF4 和 Code First 的多对多关系答案

【问题标题】：Many to many to many relationships with EF4 and Code First与 EF4 和 Code First 的多对多关系
【发布时间】：2011-01-02 20:01:27
【问题描述】：

我遇到了一个问题，我不知道如何使用 Code First 的 CTP5 和 EF4 进行表达。

编辑：在底部添加了我想通过 CF 复制的旧架构

这是我的具体场景：

团队是一个抽象概念；它应该与一组特定的球员、特定的部门、特定的赛季一起存在。

NFL 的一个具体例子：

1996（赛季）AFC Central（分区）休斯顿油人队（队）
1997（赛季）AFC Central（分区）Tennessee Oilers（队）
1999（赛季）AFC Central（分区）田纳西泰坦队（队）
2002（赛季）亚足联南部（分区）田纳西泰坦队（队）

这些都是同一个团队。我希望能够做到以下几点：

// Titans team id = 17
var myTeam = myContext.Teams.Single(t => t.Id == 17)

// display players
foreach (var p in myTeam.Seasons[1999].Players)
{
    // Do something with the p here
}

// Display current division
Response.Write(myTeam.Seasons[2002].Division.Name);

我不确定 myTeam.Seasons 的 ICollection 成员变量中的特定查询语法，但概念应该相同。

谁能解释一下您如何通过 EF4 CF CTP5 中的 CF 来表达这个概念？您将如何通过 Code First 来表达这一点？

当前的 SQL 表

CREATE TABLE dbo.Season
(
    Id                INT IDENTITY(1,1)      NOT NULL,
    LeagueId          INT                    NOT NULL,
    [Name]            NVARCHAR(50)           NOT NULL,
    [Year]            CHAR(4)                NOT NULL,
    PrevSeasonId      INT            NULL

) ON [PRIMARY];

// Primary key
ALTER TABLE dbo.Season WITH NOCHECK ADD 
    CONSTRAINT PK_Season PRIMARY KEY NONCLUSTERED (Id) ON [PRIMARY];

CREATE TABLE dbo.Division
(
    Id       INT IDENTITY(1,1)      NOT NULL,
    DefaultName   NVARCHAR(50)           NOT NULL
) ON [PRIMARY];

// Primary key
ALTER TABLE dbo.Division WITH NOCHECK ADD 
    CONSTRAINT PK_Division PRIMARY KEY NONCLUSTERED (Id) ON [PRIMARY];

// Key Relation Table
CREATE TABLE dbo.DivisionsInSeason
(
    DivisionId     INT                  NOT NULL,
    SeasonId       INT                  NOT NULL,
    DefaultName    NVARCHAR(50)         NOT NULL,
    Commissioner   UNIQUEIDENTIFIER     NOT NULL,
    ParentDivId    INT              NULL
) ON [PRIMARY];

// Primary Key
ALTER TABLE dbo.DivisionsInSeason WITH NOCHECK ADD  
    CONSTRAINT PK_DivisionsInSeason PRIMARY KEY NONCLUSTERED (DivisionId, SeasonId) ON [PRIMARY] ;

// Foreign Keys    
ALTER TABLE dbo.DivisionsInSeason WITH CHECK ADD 
    CONSTRAINT FK_DivisionsInSeason_Division FOREIGN KEY(DivisionId) REFERENCES dbo.Division(Id),
    CONSTRAINT FK_DivisionsInSeason_Season FOREIGN KEY(SeasonId) REFERENCES dbo.Season(Id),
    CONSTRAINT FK_DivisionsInSeason_User FOREIGN KEY(Commissioner) REFERENCES dbo.[User](Id);

CREATE TABLE dbo.Team
(
    Id       INT IDENTITY(1,1)      NOT NULL,
    DefaultName     NVARCHAR(50)           NOT NULL,
    DefShortName       NCHAR(3)            NULL
) ON [PRIMARY];

// Primary key
ALTER TABLE dbo.Team WITH NOCHECK ADD 
    CONSTRAINT PK_Team PRIMARY KEY NONCLUSTERED (Id) ON [PRIMARY] ;

// Key relationship table
CREATE TABLE dbo.TeamsInDivision
(
    TeamId         INT              NOT NULL,
    DivisionId     INT              NOT NULL,
    SeasonId       INT              NOT NULL,
    GeneralManager UNIQUEIDENTIFIER NOT NULL,
    Name           NVARCHAR(50)     NOT NULL,
    ShortName      NCHAR(3)         NULL

) ON [PRIMARY];

// Check Constraints
ALTER TABLE dbo.TeamsInDivision ADD  
    CONSTRAINT PK_TeamsInDivision PRIMARY KEY NONCLUSTERED (TeamId, DivisionId, SeasonId) ON [PRIMARY];

// Foreign Keys    
ALTER TABLE dbo.TeamsInDivision WITH CHECK ADD 
    CONSTRAINT FK_TeamsInDivision_Team FOREIGN KEY(TeamId) REFERENCES dbo.Team(Id),
    CONSTRAINT FK_TeamsInDivision_Division FOREIGN KEY(DivisionId) REFERENCES dbo.Division(Id),
    CONSTRAINT FK_TeamsInDivision_Season FOREIGN KEY(SeasonId) REFERENCES dbo.Season(Id),
    CONSTRAINT FK_TeamsInDivision_User FOREIGN KEY(GeneralManager) REFERENCES dbo.[User](Id);

【问题讨论】：

标签： entity-framework entity-framework-4 ef-code-first