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我在使用实体框架从我的 DbContext 对象生成的 SQL 中得到了很多重复的连接。这是我的基本结构

CatalogTable（CatalogID int 主键）

CategoryTable( CategoryID int PRIMARY KEY, CatalogID int NOT NULL )

DepartmentTable（DepartmentID int PRIMARY KEY，CatalogID int NOT NULL）

产品（CatalogID int NOT NULL，CategoryID int NOT NULL，DepartmentID int NOT NULL）

很简单，产品必须有目录、类别和部门。我已经设置了所有导航属性来反映这一点。是的，“产品”可以通过类别或部门间接关联到目录。但是因为有两种可能的路径，我选择明确指出一个产品属于一个目录。

所以问题变成了 EF 不断加入这些必需的关系，基本上为类别和部门吐出双重连接。

模型：

           //catalogs
            modelBuilder.Entity<Catalog>().ToTable("Catalog.Catalogs");
            modelBuilder.Entity<Catalog>().HasKey(k => k.CatalogID);

            //products
            modelBuilder.Entity<CatalogItem>().ToTable("Catalog.Products");
            modelBuilder.Entity<CatalogItem>().HasKey(k => k.ProductID);
            modelBuilder.Entity<CatalogItem>().HasRequired(req => req.CatalogCategory).WithMany().Map(m => m.MapKey("CatalogCategoryID"));
            modelBuilder.Entity<CatalogItem>().HasRequired(req => req.CatalogDepartment).WithMany().Map(m => m.MapKey("CatalogDepartmentID"));
            modelBuilder.Entity<CatalogItem>().HasRequired(req => req.Catalog).WithMany().Map(m => m.MapKey("CatalogID"));

            //departments
            modelBuilder.Entity<CatalogDepartment>().ToTable("Catalog.Departments");
            modelBuilder.Entity<CatalogDepartment>().HasKey(k => k.CatalogDepartmentID);
            modelBuilder.Entity<CatalogDepartment>().HasRequired(req => req.Catalog).WithMany().Map(m => m.MapKey("CatalogID"));

            //categories
            modelBuilder.Entity<CatalogCategory>().ToTable("Catalog.Categories");
            modelBuilder.Entity<CatalogCategory>().HasKey(k => k.CatalogCategoryID);
            modelBuilder.Entity<CatalogCategory>().HasRequired(req => req.Catalog).WithMany().Map(m => m.MapKey("CatalogID"));

林克：

var query = Products
    .Include(inc=>inc.CatalogCategory)
    .Include(inc=>inc.CatalogDepartment)
    .Include(inc=>inc.Catalog);



query.ToList();

生成的 Sql：

SELECT *
FROM     [Catalog].[Products] AS [Extent1]
INNER JOIN [Catalog].[Categories] AS [Extent2] ON [Extent1].[CatalogCategoryID] = [Extent2].[CatalogCategoryID]
LEFT OUTER JOIN [Catalog].[Categories] AS [Extent3] ON [Extent1].[CatalogCategoryID] = [Extent3].[CatalogCategoryID]
LEFT OUTER JOIN [Catalog].[Departments] AS [Extent4] ON [Extent1].[CatalogDepartmentID] = [Extent4].[CatalogDepartmentID]
LEFT OUTER JOIN [Catalog].[Catalogs] AS [Extent5] ON [Extent1].[CatalogID] = [Extent5].[CatalogID]

您可以清楚地看到“类别”被加入了两次；一次作为内部连接，一次作为外部连接。

这里有什么想法可以干净地（准确地）建立关系但防止重复绑定吗？谢谢！

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