[Entity Framework Code first] Relations (Data Annotation)

EF-Models(Data Annotation).cs

[Table("Suppliers")]
public class Supplier
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [StringLength(100)]
    public string CompanyName { get; set; }

    [StringLength(50)]
    public string Tel { get; set; }

    [StringLength(200)]
    public string Address { get; set; }


    #region One-to-one
    public virtual SupplierInCharge InCharge { get; set; }
    #endregion

    #region One-to-many
    public virtual ICollection<Factory> Factorys { get; set; }
    #endregion

    #region Many-to-many
    public virtual ICollection<Customer> Customers { get; set; }
    #endregion
}

[Table("SupplierInCharges")]
public class SupplierInCharge
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    [ForeignKey("Supplier")]
    public int Id { get; set; }

    [StringLength(20)]
    public string Name { get; set; }

    [StringLength(50)]
    public string Phone { get; set; }

    #region One-to-one
    public virtual Supplier Supplier { get; set; }
    #endregion
}

[Table("Factorys")]
public class Factory
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [StringLength(50)]
    public string Name { get; set; }

    [StringLength(200)]
    public string Address { get; set; }

    [Required]
    public int SupplierId { get; set; }

    #region Many-to-one
    [ForeignKey("SupplierId")]
    public virtual Supplier Supplier { get; set; }
    #endregion
}

[Table("Customers")]
public class Customer
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [StringLength(100)]
    public string Name { get; set; }

    [StringLength(200)]
    public string Address { get; set; }

    #region Many-to-many
    public virtual ICollection<Supplier> Suppliers { get; set; }
    #endregion
}