如何創建對一個表的多個表引用 - 實體框架

Question

我們要求在一個表中引用幾個表，如圖所示。

請注意，該圖表不是正確的數據庫模型，只是代表了我們的要求。 您能否在SQL Server DB和Entity Framework 6建議一種正確的實現方式？

示例：銷售訂單（在SalesOrder表中）可以包含多個文件，這些上載的文件詳細信息將存儲在UploadedFile表中。 同樣也是OrderTable和Invoice。

因此，我們需要在FileUpload表與彼此相關的表之間建立一個具有FK關系的正確數據庫模型。

注意：所有表PK都是自動增加int值，我們可能需要在將來添加更多實體（表）

Answer 1

為了向您提供替代方案，正如您所說的使用實體框架，這里是在C＃上完成的Code First實現的示例。 您可以在Visual Studio中通過程序包管理器控制台遷移創建和更新架構。 我已經使用了Fluent API來定義關系，因為這是建議的替代方案。

public class SampleContext : DbContext
{
    public SampleContext()
        : base("name=YourConnection")
    {
    }

    public DbSet<SalesOrder> SalesOrders { get; set; }
    public DbSet<CreditOrder> CreditOrders { get; set; }
    public DbSet<Invoice> Invoices { get; set; }
    public DbSet<UploadedFile> UploadedFiles { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<SalesOrder>()
            .HasKey(so => so.Id);

        modelBuilder.Entity<CreditOrder>()
            .HasKey(co => co.Id);

        modelBuilder.Entity<Invoice>()
            .HasKey(i => i.Id);

        modelBuilder.Entity<UploadedFile>()
            .HasKey(u => u.Id);

        modelBuilder.Entity<UploadedFile>()
            .HasRequired(u => u.SalesOrder)
            .WithMany(s => s.UploadedFiles)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<UploadedFile>()
            .HasRequired(u => u.CreditOrder)
            .WithMany(c => c.UploadedFiles)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<UploadedFile>()
            .HasRequired(u => u.Invoice)
            .WithMany(c => c.UploadedFiles)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<UploadedFile>()
            .Property(uf => uf.Id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        modelBuilder.Entity<SalesOrder>()
            .Property(so => so.Id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        modelBuilder.Entity<CreditOrder>()
            .Property(co => co.Id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        modelBuilder.Entity<Invoice>()
            .Property(i => i.Id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        base.OnModelCreating(modelBuilder);
    }
}

// Collections of navigation properties should be included in classes for a one-to-many relationship

public class SalesOrder
{
    public int Id { get; set; }
    public string MyColumn { get; set; }
    public IList<UploadedFile> UploadedFiles { get; set; }
}

public class CreditOrder
{
    public int Id { get; set; }
    public string MyColumn { get; set; }
    public IList<UploadedFile> UploadedFiles { get; set; }
}

public class Invoice
{
    public int Id { get; set; }
    public string MyColumn { get; set; }
    public IList<UploadedFile> UploadedFiles { get; set; }
}

public class UploadedFile
{
    public int Id { get; set; }
    public SalesOrder SalesOrder { get; set; }
    public CreditOrder CreditOrder { get; set; }
    public Invoice Invoice { get; set; }
    public string FilePath { get; set; }
    public string FileType { get; set; }
}

public class SalesOrder
{
    public int Id { get; set; }
    public string MyColumn { get; set; }
    public IList<UploadedFile> UploadedFiles { get; set; }
}

public class CreditOrder
{
    public int Id { get; set; }
    public string MyColumn { get; set; }
    public IList<UploadedFile> UploadedFiles { get; set; }
}

public class Invoice
{
    public int Id { get; set; }
    public string MyColumn { get; set; }
    public IList<UploadedFile> UploadedFiles { get; set; }
}

public class UploadedFile
{
    public int Id { get; set; }
    public SalesOrder SalesOrder { get; set; }
    public CreditOrder CreditOrder { get; set; }
    public Invoice Invoice { get; set; }
    public string FilePath { get; set; }
    public string FileType { get; set; }
}

Answer 2

在閱讀我的答案之前，請注意以下信息：

可以在以前的多個表的外鍵上找到更好的答案。

---

我的答案：

有關MDSN頁面上的創建表文檔的更多信息，請參閱此處 。

我去的設計給每個表都有自己的id作為主鍵 。 然后我用UploadedFile的表將引用添加到每個表的外鍵的形狀。

我創建了一些可能幫助您創建這些表的虛擬腳本。 請讓我知道這可不可以幫你。 謝謝！

SQL腳本：

SalesOrder表：

Create Table dbo.SalesOrder(
SalesOrderID int not null, identity primary key,
--enter whatever other columsn you have here
)

CreditOrder表：

Create Table sbo.CreditOrder(
CreditOrderID int not null, identity primary key,
--enter whatever other columsn you have here
)

發票表：

Create Table dbo.Invoice(
InvoiceID int not null, identity primary key,
--enter whatever other column you have here
)

UploadedFile表：

Create table dbo.UploadedFile(
UploadFileID int not null identity primary key,
SalesOrderID int null Foreign Key References SalesOrder(SalesOrderID),
CreditOrderID int null Foreign Key References CreditOrder(CreditOrderID),
InvoiceID int null Foreign Key References CreditOrder(InvoiceID),
--enter whatever other columns you have here
)